LIGO/Virgo G268556

A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva (IKI), E. Klunko 
(ISTP), A. Kusakin (AFIF), I. Reva (AFIF) on behalf of IKI-GW follow-up 
collaboration:

We report results of photometric observations and possible 
classifications of Pan-STARRS1 transients PS17dp, PS17fl, PS17fn, PS17gl 
(Smartt et al, GCN 20410
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 ) detected  in  the LIGO G268556 localizations 
(LIGO Scientific Collaboration, GCN 20364
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 ). Observations were conducted 
using telescopes/observatories AZT-33IK/Mondy and  Zeiss-1000/TSHAO.

===============

PS17dp	
RA   09:00:51.09
Dec +45:26:44.3

We observed the source PS17dp taking 5 observational sets in different 
epochs between Jan. 19 and 24. All observations were performed with 
filter R. The photometry is based on nearby SDSS stars.

Date		UT start	Filter	MJD		mag 	err
2017-01-19	18:24:02	R	57770.77716	16.93	0.04
2017-01-21	17:56:26	R	57774.75795	16.91	0.05
2017-01-22	17:40:22	R	57775.74680	16.90	0.05
2017-01-23	17:04:07	R	57776.72092	16.93	0.05
2017-01-24	21:17:52	R	57777.89783	17.02	0.04

The source is fading during our observations. There is an SDSS galaxy 
J090050.96+452642.7 at the position of the source with r = 17.280 +/- 
0.006 and R = 17.050 +/- 0.015 (Lupton 2005 transformation equations) 
which might be a host galaxy of the transient. At the last observational 
epoch the source faded to the host galaxy level within 1 sigma.

===============

PS17fl	
RA   08:02:09.73
Dec +28:49:44.7

We observed the source PS17fl taking 9 observational sets in different 
epochs between January 17 and March 28. All observations were performed 
with filter R.  The photometry is based on nearby SDSS stars.

Date		UT start	Filter	MJD		mag 	err
2017-01-17	16:24:04	R	57770.69727	18.15	0.10
2017-01-19	16:52:12	R	57772.71590	18.16	0.02
2017-01-21	15:21:07	R	57774.65356	18.20	0.02
2017-01-22	15:47:17	R	57775.66825	18.18	0.02
2017-01-23	15:39:48	R	57776.66306	18.17	0.02
2017-01-24	19:43:15	R	57777.82865	18.21	0.03
2017-01-25	16:24:35	R	57778.69277	18.18	0.03
2017-01-28	18:32:47	R	57781.78667	18.12	0.02
2017-03-28	17:18:32	R	57840.73404	18.22	0.03

The brightness of the source slowly decreases and in our last 
observational set has a magnitude consistent within 2 sigma with that of 
its host galaxy SDSS J080209.69+284945.3 (Chambers  et al. GCN 20437
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 ) 
with r = 18.47 +/- 0.01 and R = 18.29 +/- 0.02 (Lupton 2005 
transformation equations). If SN Ib/Ic (suggested by Chambers  et al. 
GCN 20437
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 ) then maximum can be between MJD 57761.4876 and  57770.69727 
and therefore could be related to G268556 event.

===============

PS17fn	
RA   08:05:51.40
Dec +28:42:51.9

We observed the source PS17fn taking 8 observational sets in different 
epochs between Jan. 17 and 28. All observations were performed with 
filter R.   The photometry is based on nearby SDSS stars.

Date		UT start	Filter	MJD		mag 	err
2017-01-17	17:52:24	R	57770.75515	19.51	0.16
2017-01-19	17:34:47	R	57772.74354	19.18	0.04
2017-01-21	16:15:49	R	57774.68807	19.11	0.04
2017-01-22	16:19:52	R	57775.69088	19.15	0.04
2017-01-23	16:32:34	R	57776.69970	19.15	0.40
2017-01-24	20:05:57	R	57777.84441	19.31	0.05
2017-01-25	16:53:02	R	57778.71114	19.33	0.04
2017-01-28	19:15:36	R	57781.80806	19.31	0.07

There is an SDSS galaxy J080209.69+284945.3 at the position of the 
source with r = 19.801 +/- 0.032 and R = 19.612 +/- 0.063 (Lupton 2005 
transformation equations) which might be a host galaxy of the transient. 
The source is rising above the host level for more then 3 sigma, than 
fading.The photometry of the source might be contaminated by a nearby 
galaxy J080551.85+284253.6 in 6 arcseconds to the East of the source. 
The temporal behavior of the transient allows to confirm it to be a 
supernova (Chambers  et al. 20437) with the maximum around of MJD = 
57774.68807 and therefore the source is inconsistent with the G268556 
trigger.


===============

PS17gl	
RA   08:34:50.85
Dec +61:13:02.2

We observed the source PS17fl taking 5 observational sets in different 
epochs between Jan. 19 and 25. All observations were performed with 
filter R. The photometry is based on nearby SDSS stars.

Date		UT start	Filter	MJD		mag 	err
2017-01-19	18:59:34	R	57772.80185	17.38	0.03
2017-01-21	16:48:39	R	57774.71087	17.39	0.03
2017-01-22	16:57:34	R	57775.71707	17.40	0.03
2017-01-24	20:36:10	R	57777.87095	17.56	0.02
2017-01-25	18:51:56	R	57778.79509	17.57	0.02

There is an SDSS galaxy J083450.96+611258.7 at the position of the 
source with r = 17.704 +/- 0.009 and R = 17.502 +/- 0.020 (Lupton 2005 
transformation equations) which might be a host galaxy of the transient. 
The source is fading during our observations down to the level of the 
host galaxy within 2 sigma. This may be a supernova or a GRB afterglow.

A.S. Pozanenko (IKI), V.A. Samodurov (HSE, PRAO LPI), M.O. Toropov (JSC 
Business Automation), A.E. Rodin (PRAO LPI), P.Yu. Minaev (IKI), S.V. 
Logvinenko (PRAO LPI), V.V. Oreshko (PRAO LPI) report  on behalf of 
IKI-GW follow-up collaboration:

We have investigated daily data survey of BSA radiotelescope operated at 
109.0-111.5 MHz in a survey mode (Samodurov, et al. 2015, 
http://adsabs.harvard.edu/abs/2015OAP....28..242S). At the time of 
trigger of G268556 (LIGO Scientific Collaboration, GCN 20364
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 ) the 
diagram of BSA was 10:39 hours after and 13:21 hours before passing of 
the localization area of G268556 between Dec=+15.0 deg and Dec=+42.0 deg 
(i.e. most sensitive part of the BSA diagram). We do not detect any 
source brighter than 3 Jy  (exposure of 300 s) on (UT) 2017-01-04 
23:33:00, i.e. 13:21 hours after  the G268556  trigger in Declination 
range between +15.0 and  +42.0 degrees.  We used previous passages of 
the localization region through the diagram to estimate possible 
variability of the flux and to estimate the upper limit. Result reported 
is preliminary and might be refined.

D. Svinkin, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

Konus-Wind (KW) was observing the whole sky at the time of the LIGO
event G268556/GW170104 (2017-01-04 10:11:58.599 UTC, hereafter T0;
LIGO/VIRGO Collaboration GCN Circ. 20364
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 ).

No triggered KW event happened from ~2 day before to ~1 day
after T0. The closest waiting-mode event was ~1.4 days before T0.
Using waiting-mode data within the interval T0 +/- 100 s,
we found no significant (> 5 sigma) excess over the background
in both KW detectors on temporal scales from 2.944 s to 100 s.

We estimate an upper limit (90% conf.) on the 10 keV ��� 10 MeV fluence
to 9.2x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a
typical KW short GRB spectrum (an exponentially cut off power law with
alpha=-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band
function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding
limiting peak flux is 3.3x10^-7 erg/cm^2/s (10 keV - 10 MeV, 2.944 s scale).

All the quoted values are preliminary.

The information was originally included in a LVC Circular along with 
other results at 17/03/02 14:42:59 GMT.

Reshmi Mukherjee (Barnard College and Columbia University) reports on behalf of the VERITAS Collaboration:

The VERITAS gamma-ray telescope array was used to perform follow-up observations of the localization region for the gravitational-wave candidate G268556 between 2017-01-05 07:14:53 and 11:39:39 UTC. During this period, the northern section of the 50% containment region for the event was observable at >50�� elevation from the VERITAS site and 39 consecutive exposures were performed to tile the localization region using the 3.5��-diameter field-of-view of the VERITAS telescopes. Each pointing was observed for 5 minutes, with an average spacing between pointings of 1.83�� to allow some overlap between neighboring fields. The observations cover approximately 27% of the containment probability of the event.   Unfortunately, the majority of the exposures were affected by the presence of clouds.  Furthermore, one of the four VERITAS telescopes was offline during the final two-thirds of the observations, decreasing the sensitivity by ~20%.  Preliminary results from the analysis of the VERITAS data show no significant evidence of gamma-ray emission.  Observations performed by VERITAS under clear skies using a similar observational strategy have been able to detect the Crab Nebula at high significance (>10 standard deviations) using similar exposures with all four telescopes.  Under ideal conditions, these observations of G268556 would have been sensitive to a gamma-ray source with a flux greater than ~50% of the Crab Nebula, i.e., greater than ~3 x 10^{-10} cm^{-2} s^{-1} above 100 GeV, during the time period and in the region of sky observed.  However, the sensitivity of VERITAS was reduced due to the poor weather conditions, and it is challenging to set specific limits at this time.  Questions regarding the VERITAS observations should be directed to Reshmi Mukherjee (muk@astro.columbia.edu). VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is a very-high-energy gamma-ray observatory located at the Fred Lawrence Whipple Observatory in southern Arizona, USA.

The LIGO Scientific Collaboration and Virgo Collaboration report:

We have completed a Bayesian parameter-estimation analysis of the GW
candidate G268556 (GCN 20364
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 ) under the assumption that the signal
arises from a compact binary coalescence (CBC) and using the latest
calibration of the GW strain data. The data are still found to be
consistent with a binary black hole merger.

A refined sky localization is now available and can be retrieved
from GraceDB (https://gracedb.ligo.org/events/G268556):

 * LALInference_f.fits.gz, produced using a coherent Bayesian
   analysis (Veitch et al. PRD 91, 042003) of the full GW signal
   including spin precession, and incorporating the potential
   effects of calibration errors. We regard this LALInference sky
   map as the most authoritative localization for this event.

The localization is similar in structure to previous ones (GCN
20364
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  and 20385
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 ), with two arcs tracing part of the annulus set by
the 3 ms delay in arrival time between the Hanford and Livingston
observatories. The differences compared to previous localizations
are primarily a consequence of the improved calibration of the data.

D. Svinkin, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

Konus-Wind (KW) was observing the whole sky at the times of the LIGO
events G268556, G270580, and G274296 (hereafter T0; LIGO/VIRGO 
Collaboration GCN Circ. 20364
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 , 20486
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 , and 20689
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 , respectively).
A waiting mode data gap (~100 s in duration) occurred at the time of the 
LIGO event G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738
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 ), so it was 
excluded from the analysis.

We found no significant (> 5 sigma) detection on temporal scales from 
2.944 s to 100 s using waiting mode data from both KW detectors S1 and 
S2 within +/- 100 s from each of the LIGO triggers.

The table below contains, for each of the triggers, estimates for  upper 
limits (90% conf.) on the fluence (S) for a burst lasting less than 
2.944 s and having a typical KW short GRB spectrum (an exponentially cut 
off power law with alpha=-0.5 and Ep=500 keV); and on the peak flux 
(Fpeak; on the 2.944 s scale) for a typical long GRB spectrum (the Band 
function with alpha=-1, beta=-2.5, and Ep=300 keV), both in the 10 keV - 
10 MeV band.

  UID             T0, UTC           S*    Fpeak**
G274296 2017-02-17 06:05:53.050   9.6     3.2
G270580 2017-01-20 12:30:59.350   9.9     3.1
G268556 2017-01-04 10:11:58.599   9.2     3.3

* in units of 10^-7 erg/cm2
** in units of 10^-7 erg/cm2/s

All the quoted values are preliminary.

G. Hosseinzadeh, I. Arcavi, D. A. Howell, C. McCully (Las Cumbres
Obs./UCSB), and S. Valenti (UC Davis) report a spectrum of EM candidate
iPTF17cf/PS17fr (GCN 20398
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  & 20410) associated with gravitational wave
event G268556 (GCN 20364
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 ) obtained 2017 January 27.3 UT with the robotic
FLOYDS instrument mounted on the Las Cumbres Observatory 2-meter telescope
on Haleakala, Hawai'i. The spectrum shows broad H-alpha and H-beta emission
and possible narrow [O III] emission at redshift z~0.19, suggesting an AGN
classification (c.f. GCN 20459
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 ).

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration:

The ANTARES Collaboration has reported in GCN 20370
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 , no up-going muon neutrino candidate event within the 90% contour during a +/- 500s time-window centered on the G268556 event time.

We use this non-detection to derive a neutrino (nu_mu+antinu_mu) spectral fluence instantaneous upper limit at 90% C.L. (phi_0 in GeV/cm^2), defined as dN/dE = phi_0* E^{-2} assuming a E^{-2} neutrino spectrum. The result is reported in https://www.cppm.in2p3.fr/~dornic/events/G268556_fluenceE2.png <https://www.cppm.in2p3.fr/~dornic/events/G268556_fluenceE2.png> (gwantares/ANT@GW) as a function of the source direction. These neutrino fluence limits range between 1 and 3 GeV/cm^{2} depending on the source direction. For a E^{-2} neutrino spectrum, 90% of ANTARES signal neutrinos are in the energy range from 2.8 TeV to 3.2 PeV (mean value over the sky).

From the 3D GW localization and the neutrino spectral fluence upper-limits, the preliminary upper limits on the total energy radiated in high-energy neutrinos over the GW skymap are computed for the progenitor of G268556 as a function of the source direction assuming a a E^{-2} neutrino spectrum integrating in the range [100 GeV-100 PeV]: https://www.cppm.in2p3.fr/~dornic/events/G268556_energyE2.png <https://www.cppm.in2p3.fr/~dornic/events/G268556_energyE2.png> (gwantares/ANT@GW). The total neutrino emission limits range between 10^{54} and 10^{55} ergs.

ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere. It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky.

M. Serino (RIKEN), N. Kawai, S.Sugita (Tokyo Tech), H. Negoro (Nihon U.), 
S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), 
Y. E. Nakagawa (JAMSTEC),
T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T.  Takagi, M. Matsuoka (RIKEN), 
N.Isobe, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), 
H. Tsunemi, R. Shomura (Osaka U.), 
M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), 
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), 
M. Yamauchi, K. Furuya (Miyazaki U.), 
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

We examined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained
in the orbit and the day after the LVC trigger
G268556/GW170104 at 2017-01-04 10:11:58.599 UTC (GCN 20364
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 ).

In the 92-min orbit, MAXI/GSC scanned more than 80% 
of the whole sky, which includes 89.3% of the 
90% regions in the bayestar skymap.
One day image covers 95.2% of the 90% regions 
in the bayestar skymap.
No significant new source was found in these images.

The upper limits for the X-ray flux are different depending 
on the part of the sky.
For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained 
from the one-orbit and oneday images are  
19 (56) mCrab and 5 (16) mCrab, respectively.

MAXI/GSC also observed the position of GRB 170105A 
(GCN Circ. 20377
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 , 20390
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 , 20406
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 ). The first scan after the burst
was at 2017-01-05T06:47 (UT). No significant emission was observed
at the position at the scan. The 1-sigma (3-sigma) upper limits in 2-20 keV 
are 18 (54) mCrab.

N.Tyurina, V.M.  Lipunov, O.Gress, E. Gorbovskoy, V.G. 
Kornilov, P.Balanutsa,  A.Kuznetsov, V.Shumkov, M.I.Panchenko, A.V.Krylov, 
I.Gorbunov
Lomonosov  Moscow State University, Sternberg Astronomical Institute

D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

N.M. Budnev, O. Gress, K. Ivanov
Irkutsk State University

V.Yurkov, Yu.Sergienko, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk


1) MASTER OT J072347.17+041144.0 discovery

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) 
= 07h 23m 47.17s +04d 11m 44.0s on 2017-01-09.07133 UT.
The OT unfiltered magnitude is 17.5m (mlim=19.3).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image on 2015-05-17.70236 UT with unfiltered mlim= 
19.0m.
Spectral observations are required.

The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/072347.17041144.0.png

2) MASTER OT J073310.71-012307.3 discovery - dwarf nova outburst

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 07h 
33m 10.71s -01d 23m 07.3s on 2017-01-15.07407 UT.
The OT unfiltered magnitude is 18.0m (mlim=18.7). The OT is seen in 2 
images. The second image on 2017-01-15.07656 has m_OT=18.3 (possible UGSU 
type?). There are 2 images on 2017-01-18 18:44:23UT (MASTER-Kislovodsk) 
with m_OT=18.8 (mlim=19.8).
We have reference images on 2016-10-13.09314 UT with unfiltered mlim= 
19.0m (MASTER-SAAO), on 2013-02-11 18:07:22UT with 
mlim=19.7(MASTER-Kislovodsk).
There were previous outbursts in MASTER databases:
on 2013-12-27 20:41:41.17 with m_OT=18.5 (2 images in MASTER-Kislovodsk)
on 2015-12-17 17:22:22.72 with m_OT=17.5 (2 images in MASTER-Tunka)

Spectral observations are required.
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/073310.71-012307.3.png

3) MASTER OT J080700.56+162008.7 detection

MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 08h 
07m 00.56s +16d 20m 08.7s on 2017-01-19.13492 UT.
The OT unfiltered magnitude is 19.3m (limit 19.8m).
The OT is seen in 2 images (2017-01-19 03:14:17.943, 03:10:37.397). We 
have reference image without OT on 2016-11-09.20727 UT with unfiltered 
magnitude limit 20.0m.
There is Sloan star with gmag=22.9, r=21.2, i=19.6
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=121.75233333333+16.335738888889&-c.rs=5

Spectral observations are required.
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/080700.56162008.7.png

4)  MASTER OT J075227.62+113311.6 discovery - QSO flare

MASTER-SAAO auto-detection system
discovered OT source at (RA, Dec) = 07h 52m 27.62s +11d 33m 11.6s on 
2017-01-08.99171 UT.

The OT unfiltered magnitude is 18.5m (mlim=19.5).
The OT is seen in 8 images. There is no minor planet at this place.
We have reference image on 2015-05-25.70605 UT with unfiltered mlim= 
19.4m.
Spectral observations are required.
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/075227.62113311.6.png

5) MASTER OT J063256.50-212333.4 detection - possibly UVCet flare

MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 06h 
32m 56.50s -21d 23m 33.4s on 2017-01-18.91929 UT.
The OT unfiltered magnitude is 17.6m (limit 19.7m).

The OT is seen in 5 images, UVCet preliminary (J-K=0.8)
2017-01-18 21:41:32.849 16.0
2017-01-18 21:45:12.99 16.2
2017-01-18 21:48:58.848 16.5
2017-01-18 22:03:47.638 17.5

We have reference image without OT on 2015-12-18.08299 UT with unfiltered 
magnitude limit 20.7m.
Spectral observations are required.
The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/063256.50-212333.4.png

6)  MASTER OT J074554.47+283123.8 discovery

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )
discovered OT source at (RA, Dec) = 07h 45m 54.47s +28d 31m 23.8s on 
2017-01-05.04067 UT.

The OT unfiltered magnitude is 18.4m (mlim19.7=).
The OT is seen in 2 image. We have reference image on 2017-01-05.03814 UT 
with unfiltered mlim= 19.6m.
There is no known objects inside 3" in VIZIER database, but there is very 
faint source at Sloan image (rmag<23)
Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/074554.47283123.8.png


7)  MASTER OT J081016.59+335347.5 discovery - PSN in 1.9"W, 2.4"S of 
PGC2040653

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 08h 10m 16.59s +33d 53m 47.5s on 2017-01-08.15065 UT.
The OT unfiltered magnitude is 17.0m (limit 17.6m).

The OT is seen in 2 images. There is no minor planet at this place.
We have reference image without OT on 2016-11-02.89640 UT with unfiltered 
magnitude limit 19.8m.
Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/081016.59335347.5.png


8) MASTER103001.37+680122.3 discovery - dwarf nova outburst?

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 10h 30m 01.37s +68d 01m 22.3s on 2017-01-07.12512 UT.
The OT unfiltered magnitude is 18.5m (limit 20.3m).

The OT is seen in 2 image. There is no minor planet at this place.
There is m_OT=20.1 on 2017-01-06 02:18:08UT (dwarf nova?), it means 
amplitude of current outburst more then 1.5mag
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/103001.37680122.3.png

9) MASTER OT J073330.60+203432.7 discovery - dwarf nova outburst?

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 07h 
33m 30.60s +20d 34m 32.7s on 2017-01-18.65299 UT.
The OT unfiltered magnitude is 18.1m (limit 19.5m).

The OT is seen in 2 images. There is no minor planet at this place.
We have reference image without OT on 2017-01-05 20:20:59 with mlim=19.8, 
on 2011-11-28.89471 UT with unfiltered magnitude limit 20.0m.
There is Sloan blue star with rmag=19.80, it means current outburst 
amplitude more then 1.9m
http://skyserver.sdss.org/dr9/en/tools/quicklook/quickobj.asp?id=1237660564038877690

Spectral observations are required.


10) MASTER OT J084411.47+670931.6 - flare, >1.5mag Ampl
MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 08h 44m 11.47s +67d 09m 31.6s on 2017-01-20.72236 UT.
The OT unfiltered magnitude is 19.1m (limit 20.1m).

The OT is seen in 6 images. There is no minor planet at this place.

We have reference image without OT on 2012-10-20.89072 UT with unfiltered 
magnitude limit 19.8m.
There is USNO B1 star with R2=20.6, APM blue mag=22.04, it means MASTEr 
W=20.9, Ampl of current outburst >1.5

Spectral observations are required.


11) MASTER OT J102428.83+641859.1 discovery - QSO flare

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 10h 
24m 28.83s +64d 18m 59.1s on 2017-01-07.81205 UT.
The OT unfiltered m is 17.8m (limit 20.2m).

The OT is seen in 23 images in history. Last QSO (Sloan red=20.5) 
outbursts detected by MASTER:
2015-03-09 17:00:10.572  19.0
2017-01-05 14:58:23.595 17.9
2017-01-07 19:29:21.053 17.8
2017-01-07 19:45:55.751 17.8

We have reference image without OT on 2016-08-20 18:40:31 with mlim=18.7, 
on 2015-07-10.70841 UT with unfiltered mlim=19.6m.

Spectral observations are required.



12) MASTER OT J075227.69+113313.2 discovery - QSO flare


MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 07h 
52m 27.69s +11d 33m 13.2s on 2017-01-06.70229 UT.
The OT magnitude in unfiltered is 18.4m (limit 19.0m).

The OT is seen in 2 images.
We have reference image without OT on 2015-10-19.86133 UT with unfiltered 
19.3m.

There is Sloan source in 1" with red mag 19.819, GALEX source(accretion), 
QSO candidate (Richards+, 2015).

Spectral observations are required.

13) MASTER OT J081506.13+381123.3 discovery - PSN in 11"E,2.8"N of 
PGC2120251

MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global 
Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at 
(RA, Dec) = 08h 15m 06.13s +38d 11m 23.3s on 2017-01-16.01742 UT.
The OT unfiltered magnitude is 16.9m (limit 18.6m).
The OT is seen in 2 images in MASTER-Kislovodsk and in 2 in MASTER-SAAO 
(2017-01-18 00:38:36UT).
There is no minor planet at this place.
We have reference image without OT on 2016-11-29.91344 UT with unfiltered 
magnitude limit 20.1m.
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/081506.13381123.3.png

14) MASTER OT J074928.00+190452.3 discovery ( 2017-01-19 22:23:28.536UT, 
mOT=17.4) = current outburst of UG (dwarf nova) CSS 090331:074928+190452
15) MASTER OT J051306.58-261951.9 detection (2017-01-11 23:36:39.213, 
m_OT=16.1) = current outburst of UGSU  ASASSN-14kf
16) MASTER OT J224258.06-194551.5 detection  (2017-01-04 19:44:11.46, 
m_OT=13.7) = current outburst of UGSU (Dwarf nova) ASASSN-14hs
17) MASTER OT J101511.20+812418.1 discovery () = current outburst of dwarf 
nova ASASSN-15gq / UGSU
18) MASTER OT J101813.00+715542.7 discovery 2017-01-04 20:20:00.35UT, 
m_OT=15.1) = current outburst of dwarf nova CI UMa (UGSU)
19) MASTER OT J075107.56+300628.0 discovery (2017-01-06 18:33:32.877, 
m_OT=15.3) = current outburst of dwarf nova  SDSS J075107.50+300628.4
20) MASTER OT J105811.78+811432.6 discovery - BLA flare in GW170401 field 
, publishied GCN20392
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21
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 ) MASTER OT J090021.21+635049.7 - SN, publishied GCN20381
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Zach Golkhou (ASU), Nat Butler (ASU), Neil Gehrels (GSFC), Alexander
Kutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC), and Alan M.
Watson (UNAM) report:

We observed a number of iPTF candidates (Kasliwal et al. LVC GCN#20398
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 )
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional on Sierra San Pedro M��rtir from 2017/01 11.28--11.30 UTC (6.85
days since the GW trigger; Shawhan et al. LVC GCN #20364
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 ) and again from
2017/01 12.44--12.46 UTC.

At positions consistent with each iPTF source position, we report riZY
photometry for the probable host galaxy from the first epoch. In comparison
with the SDSS DR9 and 2MASS catalogs, we obtain:

# Source   r                   (dt_r)  i                     (dt_i)   Z
             (dt_Z)   Y                (dt_Y)
iPTF17ce 19.84+/-0.04 (0.36) 18.92+/-0.02 (0.36) 18.37+/-0.02 (0.07)
18.35+/-0.03 (0.07)
iPTF17ck 18.17+/-0.01 (0.71) 17.59+/-0.01 (0.71) 17.63+/-0.01 (0.15)
17.33+/-0.01 (0.15)
iPTF17dz   ...                          19.09+/-0.01 (0.51) 19.30+/-0.03
(0.22) 19.23+/-0.04 (0.22)
iPTF17ef 19.18+/-0.02 (1.07) 18.92+/-0.02 (1.07) 18.86+/-0.03 (0.22)
18.59+/-0.02 (0.22)
iPTF17ei 16.77+/-0.01 (1.38) 16.37+/-0.01 (1.38) 16.17+/-0.01 (0.29)
15.97+/-0.01 (0.29)

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the source direction. Exposure times (dt) are reported in
hours.

We find no evidence for variation in flux at >2-sigma confidence from an
image subtraction analysis between our two epochs.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.

P.A Evans (U. Leicester), A. Corsi (TTU), J.A. Kennea (PSU), S.D. 
Barthelmy (NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld 
(UCL-MSSL), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko 
(NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. 
D'Avanzo (INAF-OAB), V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi 
(ASI), C. Gronwall (PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin 
(UCL-MSSL), A.Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall 
(NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester),  J.A. 
Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U.  Leicester), 
J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L.
Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti
(INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja
(NASA/GSFC/UMCP), M.M. Kasliwal (Caltech), S.R. Kulkarni (Caltech), D.A. 
Frail (NRAO), N.T. Palliyaguru (TTU) report on behalf of the Swift and 
iPTF GW follow-up teams:

Swift has performed follow-up observations of the source iPTF17cw 
(Kasliwal et al., LVC Circ. 20398; Kupfer et al., LVC Circ. 20419). 
Swift-XRT collected 1.3 ks of data from 790.6 ks to 802.8 ks after the 
GW trigger.

No X-ray events were detected at the location of iPTF17cw. The 3-sigma 
upper limit at this location was 5.3e-3 ct/sec (0.3-10 keV). Assuming a 
typical AGN spectrum (NH=3e20 cm^-2, Gamma=1.7) this corresponds to a 
flux of 2.19e-13 erg cm^-2 s^-1.

M. E. Huber (IfA), K. C. Chambers (IfA), T.-W. Chen (MPE),
S. J. Smartt, (QUB), K. W. Smith (QUB), D. R. Young, D. E. Wright,
E. Kankare, R. Kotak, C. Inserra (QUB), M. Coughlin (Harvard),
L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest
(STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard)
J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA)

Further to our Pan-STARRS campaign (Smartt et al, GCN 20410
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 ) and
classification of transients (Chambers et al. GCN 20437
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 ) we report
spectra of two further objects at the cores of galaxies.

--------------------------------------------------------------
PS17fr - possible luminous nuclear SN or TDE
---------------------------------------------------------------

PS17fr was discovered coincident with the nucleus of an r=18.36 galaxy
(SDSS J081152.10+252521.3), with a photometric redshift z=0.199.  The
magnitude on the first epoch MJD=57758.433 (from the difference image)
was i=19.2, rising 0.6 mag in 3 days.

A spectrum with the UH2.2m + SNIFS (R~1300, 3200-10000A) was taken on
MJD=57997 and shows broad H-alpha, H-beta and He I 5876. The line
profiles are asymmetric. The strong H-alpha has a width at half
maximum of 5200 km/s, but is either multicomponent or significantly
asymmetric with a red excess. Assuming the centroid of the peak
velocity is representative of the host and transient, then 
z = 0.1862 +/- 0.0003.

This implies an absolute magnitude of M_r = -21.1. The object may be a
a superluminous supernova of type II or IIn.  We note that it is
within the volume defined by the LALInference 3D map, at a luminosity
distance of 918 Mpc (Ho=69, Omega_M=0.3, Omega_Lam=0.7). 

As this is a nuclear transient, AGN activity is possible. But we see
no strong [N II], [OIII] or [O II]. A weak feature close to, but not
exactly at the expected position of [O III] 5007 is visible in the
SNIFS data. Another spectrum is required to confirm. 
A tidal disruption event is also a possible explanation.

In summary this is an unusually luminous transient within the LIGO
skymap and at a distance consistent with the central 80% of the
probability distribution. Further multi-wavelength follow-up is
encouraged to determine its nature.
Coords : 08:11:52.11 +25:25:21.4 (J2000)

-------------------------------------------------------------
PS17er - probable AGN/Seyfert 2 variability
-------------------------------------------------------------

PS17er is also a rising transient (now at i=20) at the core of the
r=19.2 galaxy SDSS J084157.26+405507.6. A spectrum with Gemini-N+GMOS
(R400 grating, 4491-8778 A) on 57764.4223666319 shows it to be at a
redshift of z=0.4064 from the [O III] 4959/5007 Angs, implying M_g =
-21.3.  These lines have a resolved width of 700 km/s, and there is a
broader (4000 km/s) H-beta line in emission. 

The ratio Log([OIII]/Hb) ~ 0.8, is normal for an AGN.  In Pan-STARRS
regular survey mode, we have seen various detections of i ~ 20
variability. Hence we consider this as likely ongoing Seyfert 2
activity, similar to episodes previously detected in PSST (Huber et
al. 2015, ATel 7153).

M. Boer, R. Laugier, K. Noysena (ARTEMIS - CNRS/UCA/OCA), A. Klotz (IRAP 
- CNRS/UPS) report on behalf of the TZAC collaboration.

The TAROT network of telescopes has observed part of the error box of 
the GW trigger G268556 (Shawman et al., GCN 20364
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 ). The observations 
took place at TCA (TAROT OCA Calern observatory, France), TCH (TAROT 
Chile, ESO La Silla Observatory), and TRE (TAROT Les Makes Observatory, 
La R��union Island, France) during their respective nights of January 5-6 
and 6-7, 2017. The field of view of TCA and TCH is 1.86�� (square), and 
4.2�� for TRE. 4 fields have been observed by TCA, 5 for TCH and 9 for 
TRE, resulting in a total of 175 sq. deg. explored in the error box. The 
source ATLAS17aeu (Tony et al., GCN 20382
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 ) was not included in our 
fields. The exposures lasted 120s with no filter, resulting in 
approximate limiting magnitude of R < 17 for TCA and TCH (depending on 
the conditions and Moon) and 16 for TRE. The list of the fields is given 
below.

We have checked the TCA and TCH fields and found no new candidate 
astrophysical transient sources. Analysis is still underway for TRE.

List of field centers (J2000):

TCA (1.86�� x 1.86��)

#0

	

08h51m11s

	

+47d58m55s

#1

	

08h43m27s

	

+46d02m16s

#2

	

08h56m47s

	

+49d53m15s

#3

	

09h05m31s

	

+52d01m07s

TCH (1.86�� x 1.86��)

#0

	

23h49m18s

	

-36d03m12s

#1

	

23h58m29s

	

-37d19m07s

#2

	

00h08m10s

	

-38d22m09s

#3

	

00h17m47s

	

-39d19m59s

#4

	

23h34m38s

	

-33d52m51s


TRE (4.2�� x 4.2��)

0

	

23h44m45s

	

-35d28m08s

1

	

00h02m19s

	

-37d20m19s

2

	

00h22m48s

	

-39d26m19s

3

	

00h44m36s

	

-42d01m15s

4

	

01h07m43s

	

-43d40m09s

5

	

23h31m33s

	

-32d11m14s

6

	

23h18m49s

	

-28d00m31s

7

	

23h03m54s

	

-24d30m28s

8

	

22h52m18s

	

-20d50m51s

K. C. Chambers (IfA), T.-W. Chen (MPE), S. J. Smartt, (QUB),
M. E. Huber (IfA), K. W. Smith (QUB), D. R. Young, D. E. Wright (QUB),
M. Coughlin (Harvard), L. Denneau, H. Flewelling, A. Heinze,
E. A. Magnier (IfA), A. Rest (STScI), B. Stalder (IfA),
A. S. B. Schultz, C. W. Stubbs (Harvard) J. Tonry, C. Waters,
R. J. Wainscoat, H. Weiland (IfA)


Further to Chambers et al. GCN 20410
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 , we report initial results of
spectroscopic classifications. We used Gemini-North + GMOS (R400
grating, 4491-8778 Angs) on MJD = 57761 (2017 Jan 08) to target
objects which had either evolving lightcurves (rising/falling) and/or
no obvious host galaxy. We report three classifications : 

PS17fj is a SN Ia at redshift = 0.239
PS17fl is most likely a SN Ib/Ic at or before peak at z=0.018
PS17fn is most likely a young type SN II at z=0.074 

Further details as follows  

PS17fj :
The best matches are SN1999ef +7d (normal-Ia), SN2001fe +6d
(normal-Ia). Reasonable fits are also found for the 91T-like SN2003fa
91T-like. With an absolute mag of -19.7 mag, this is brighter than
normal Ia, but typical for 91T-like. There is no host in SDSS, but the
deeper PS1 3Pi stack (Chambers et al. 2016 arXiv 16120.5560) , shows a
faint source at r~22.6 which is likely a dwarf galaxy host.  The
source is now fading.

PS17fl :
The spectrum has strong emission lines from the r=18.47 host galaxy,
giving the redshift of z=0.081. It is also close to the centre of the
compact host in the PS1 reference frames (0.7 arcsec) and the GMOS
spectrum is likely contaminated with continuum flux from the host as
it is not resolved in the 2D images. The spectrum has a blue
continuum, consistent with the host galaxy. If a galaxy continuum
(matched to the SDSS colours) is subtracted then reasonable fits to
the spectrum are found for a Ib or Ic SN at or before peak.  It is
possible it is still rising, as a fit to SN2005bf at -8days is
reasonable.  The distinct lack of Si II means a Ia is unlikely. It is
currently i = 20.17, or M_i ~ -17.7.


PS17fn : 
PS17fn shows a blue continumm and galaxy emission lines of H-alpha and [SII]
at z = 0.074. There is a broad and shallow emission profile at the
position of H-alpha. The spectrum is noisy below 5000Angs (restframe),
but is rising with a continuum blackbody temperature around 10,000K
There is no good match from either SNID and GELATO. It is likely a
very young type II, which is consistent with the lightcurve rise of
0.6mag in 3 days. The current mag of i=20.27 corresponds to an
absolute mag of M_i ~ -17.4.

D.Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D.K. Galloway, E.Rol, E.Thrane (Monash U.), V.Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Maund, J.Mullaney (U. Sheffield), G.Ramsay (Armagh O.), P.O'Brien, R.Starling (U. Leicester)

On behalf of the GOTO collaboration:

We have analysed our SWASP imaging related to G268556 (GCN #20364
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 , spanning MJD 57758.043-57758.210) for evidence of ATLAS17aeu. Our first imaging window following G268556 spans 9-5 hours before the reported detections in Tonry et al. (GCN #20382
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 ) and end 1 hour before GRB170105A (GCN #20387
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 ). We do not find any evidence for an optical source at the ATLAS17aeu position. We combined 3 sets of images not affected by clouds and achieve the following 5-sigma upper limits:

MJD (mid):              g limit:    r limit:
57758.05948013   >17.7       >17.0
57758.09198558   >17.6       >16.9
57758.20992235   >17.0       >16.3

These photometric limits were derived by crossmatching field stars with the APASS survey. Considering the reported optical flux evolution of ATLAS17aeu (GCN #20382
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 , #20393
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 , #20397
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 , #20407
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 , #20416
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 ) and extrapolating to earlier times, we would have expected to detect ATLAS17aeu if its peak optical flux preceded GRB170105A. Our non-detections thus further corroborate associating ATLAS17aeu with the optical afterglow of GRB170105A.

R. Itoh,  Y. Tachibana, Y. Saito, T. Yoshii, T. Fujiwara, Y. Ono,  K.
Morita, K. Saisho,Y. Yatsu, and N. Kawai (Tokyo Tech),
C.-C., Ngeow (National Central University), L. P. Singer (NASA/GSFC),
M. M. Kasliwal (Caltech)

report on behalf of the GROWTH collaboration:

We observed the field of the optical candidate reported by Singer et al.
(LVC GCN 20401
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 ) with the 50cm Japanese telescope at Akeno Observatory
(Japan) and the 40cm Telescope (SLT)  with Apogee CCD at Lulin Observatory
(Taiwan). We obtained the g, V, R and I bands image on 2017-01-09 and
2017-01-10 (UTC). The observed objects are listed below (3-sigma upper
limits). We note that iPTF17fu, iPTF17fs, iPTF17ft, iPTF17fw, iPTF17gr,
iPTF17gv and iPTF17gw contained the host galaxy but
subtraction of host galaxy were not applied.

#Time(UT) exposure[sec] ra[deg.] dec[deg.] V[mag.] V-error Name
2017-01-09T18:13:02 300.0 162.900034 +69.833971 18.99 0.13 iPTF17fs

#Time(UT) exposure[sec] ra[deg.] dec[deg.] g[mag.] g-error R[mag.] R-error
I[mag] I-error Name
2017-01-09T11:40:51.95 660.0 162.900034 +69.833971 >18.7 -- >19.0 -- >18.7
-- iPTF17fs
2017-01-09T16:31:03.65 2580.0 156.366148 +71.757620 16.46 0.07 15.46 0.02
14.97 0.03 iPTF17fw
2017-01-09T15:12:28.36 2640.0 159.042893 +69.146836 >19.1 -- >18.9 -- >18.5
-- iPTF17ge
2017-01-09T19:58:36.97 2040.0 199.058226 +76.521298 19.0 0.2 18.4 0.2 17.9
0.4 iPTF17gs
2017-01-09T12:48:30.17 2340.0 176.227516 +82.619152 16.52 0.07 15.49 0.03
14.87 0.03 iPTF17gv
2017-01-09T18:31:04.09 1380.0 178.409537 +72.864968 17.6 0.2 16.59 0.09
15.89 0.04 iPTF17gw
2017-01-09T19:07:24.90 1560.0 194.925476 +75.016124 19.9 0.2  >19.7 --
>18.7 -- iPTF17hh
2017-01-09T17:31:38.92 1920.0 180.885869 +72.050360 18.7 0.3 18.7 0.4 18.5
0.5 iPTF17hi
2017-01-09T19:48:39.40 480.0 191.763759 +76.839773 19.0 0.2 18.5 0.2 >18.1
-- iPTF17gt
2017-01-09T13:02:59.53 480.0 165.400920 +68.097753 >17.3 -- >18.0 -- >17.4
-- iPTF17hc
2017-01-10T18:52:33.53 1980.0 201.323053 +78.426314 16.23 0.09 15.21 0.03
14.84 0.03 iPTF17ft
2017-01-10T20:41:03.31 300.0 235.823172 +74.750334 18.8 0.3 17.6 0.2 17.0
0.2 iPTF17gm
2017-01-10T20:03:36.84 1920.0 232.045095 +74.611299 19.5 0.4 18.8 0.3 17.0
0.2 iPTF17gn
2017-01-10T19:41:27.53 480.0 195.818782 +80.173138 >18.9 -- >18.5 -- >18.0
-- iPTF17hf
2017-01-10T12:35:41.66 1140.0 192.417627 +80.149750 17.52 0.07 16.14 0.03
15.54 0.03 iPTF17fu
2017-01-10T18:12:54.94 2100.0 193.895770 +79.226903 17.51 0.04 16.22 0.02
15.64 0.02 iPTF17gr
2017-01-10T15:12:41.65 2340.0 194.101611 +78.204729 19.6 0.3 18.6 0.2
iPTF17gu
Observations of this source were taken as part of the GROWTH network (
http://growth.caltech.edu).

A. Corsi (TTU), M.M. Kasliwal (CalTech), S.B. Cenko (NASA/GSFC), D.A. Frail (NRAO)
report on behalf of a larger collaboration:

We observed the position of the broad-lined type Ic supernova iPTF17cw (Kasliwal et 
al. LVC GCN#20398
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 ; Kupfer et al. LVC GCN#20419
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 )located in the error region of LIGO/
Virgo G268556 (LVC GCN#20364
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 ) with the Karl G. Jansky Very Large Array (VLA) in its 
A configuration. The observations started on 10 Jan 2017 02:51:16 UTC, ended on 10 
Jan 2017 03:51:00 UTC, and were carried out in C-band (central frequency of about 
6 GHz).

A provisional reduction of our data shows a radio source located at the position of 
iPTF17cw. For this source, we measure a radio flux of (38.1+/-7.3) uJy at 6.2 GHz. 
We caution that at the present time we do not know whether this source is variable. 
Further observations are planned.

We thank the VLA staff for rapidly executing these observations.

A. Giunta, A. Di Paola, M. Centrone, N. Napoleone, P. Tedesco (INAF-OAR), S. Covino, P. D'Avanzo, A. Melandri (INAF-OAB), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC),  M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPD), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), A. Grado (INAF-OAC), G. Greco (Urbino University/INFN Firenze), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Palazzi (INAF-IAFS Bo), E. Pian (SNS-Pisa), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), A. Rossi (INAF-IASF Bo), G. Stratta (Urbino University/INFN Firenze), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L . Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report:


We carried out observations of LIGO/Virgo G268556 (LVC, GCN 20364
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 ) with the 0.9m Schmidt telesope located at the Campo Imperatore Observatory (Italy). The observations were taken in the r-sloan band on 2017-01-04 between 18:49:58 UT and 20:31:15 UT (8.6-10.3 hours after the trigger) under poor sky conditions. 
The covered area of ~ 6 square degrees captured a containment probability of ~1% of the LALInference map (LVC, GCN 20385
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 ). The area is divided in 5 pointings of 1.15x1.15 degrees and 120 sec exptime each. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky) starting from the high probability region of the bayestar skymap and taking into account the airmass.

The 5 pointings are centered on the following coordinates RA, Dec (J2000):
131.6290   +47.8526
131.6304   +48.8528
132.9895   +47.8364
132.9902   +48.8390
132.9896   +49.8408

A preliminary analysis of these data reveals no obvious candidate counterpart down to a 3sigma limiting magnitude r ~ 17.0 (AB, calibrated against the SDSS DR13).

K. P. Mooley, R. P. Fender (Oxford), A. Horesh (HUJI) report on behalf 
of a larger collaboration

We observed the optical transient ATLAS17aeu (Tonry et al., LVC GCN 
20382
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 ) located in the error region of LIGO/Virgo G268556 (LVC GCN 20364
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 ) 
with the AMI Large Array on 2017 Jan 07.04 UT. At 15.5 GHz, the flux 
density of the source is 336+/-20 uJy. We are currently monitoring this 
source.

We thank the AMI staff for scheduling this observation. Since this 
source is likely the afterglow of GRB 170105A (e.g. Kasliwal et al., LVC 
GCN 20393
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 ; Chambers et al., LVC GCN 20407
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 ), we will be updating the 
AMI-GRB database (http://4pisky.org/ami-grb/) with the measurements.

A.Y. Lien (GSFC/UMBC), S.D. Barthelmy (NASA/GSFC), D.M. Palmer (LANL),
T. Sakamoto (AGU), A. A. Breeveld (MSSL-UCL), A.P. Beardmore (U. Leicester),
D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC),
G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),
V.D'Elia(ASDC), P.A. Evans (U. Leicester), N. Gehrels (NASA/GSFC),
P. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU),
H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), D. Malesani (DARK/NBI),
F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester),
J.A. Nousek (PSU), S.R. Oates (Uni. of Warwick), P.T. O'Brien (U. Leicester),
J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester),
M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),
M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

We report the search results in the BAT data within T0 +/- 100 s of the
LIGO event G268556 (Shawhan et al. GCN Circ. 20364
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 ) , where T0 is the
LIGO trigger time (2017-01-04T10:11:58:599 UTC).

The BAT pointing position at T0 is
RA = 166.157 deg,
DEC = 38.204 deg,
ROLL = 81.247 deg.
The BAT Field of View (>0.1 partial coding) covers 48% of the integrated
LIGO localization probability.

There are no BAT event data in this time range (usually event data are only
collected for ~ 1000 s around the BAT trigger time). Also, no significant
detections (signal-to-noise ratio > 4 sigma) are found in the BAT raw light
curves with time bins of 64 ms, 1 s, and 1.6 s, respectively. Assuming an
on-axis (100% coded) short GRB with a typical spectrum in the BAT energy range
(i.e., a simple power-law model with a power-law index of -1.32; Lien & Sakamoto
et al. 2016), the 4-sigma upper limit in the 1-s binned light curve corresponds
to a flux upper limit (15-350 keV) of ~ 6.0 x 10^-8 erg/s/cm^2.

BAT retains decreased, but significant, sensitivity to rate increases for
gamma-ray events outside of its FOV. About 19% of the integrated LIGO localization
probability was outside of the BAT FOV but above the Earth's limb from Swift's
location, and the corresponding flux upper limits for this region are within roughly
an order of magnitude of those within the FOV.

A.K.H. Kong (NTHU/Oxford), J. Mao, X. Hou, J. Wang, and J.-M. Bai  (YNAO)

We observed the field of the optical transient ATLAS17aeu (Tonry et al.,
LVC GCN 20382
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 ; Kasliwal et al., GCN 20398
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 ) that is within the error region
of LIGO/Virgo G268556 (LVC, GCN 20364
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 ) with the 2.4-m GMG telescope at the
Lijiang Observatory in Yunnan, China. We obtained an R-band image with the
Yunnan Faint Object Spectrograph and Camera (YFOSC) on 2017-01-07 14:55:35
UT. ATLAS17aeu was not detected with a 3-sigma limit of about R~23 mag.

ATLAS17aeu was detected with i=21.9 mag on 2017-01-07 08:05:33 UT (Kasliwal
et al., GCN 20398
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 ) and was proposed to be the afterglow of GRB 170105A. Our
observation indicates that the source is fainter than the suggested
power-law decay. However, due to the use of different filters in ATLAS,
Palomar, and Lijiang, the lightcurve should be treated with caution.

I.A. Steele, A.S. Piascik, M.J.Darnley, C.M. Copperwheat (LJMU), M. M. Kasliwal (Caltech) and D.A. Perley (Dark Cosmology Centre, Copenhagen) on behalf of a lager collaboration.

We report spectroscopy of the iPTF counterparts iPTF17bv and iPTF17ck.  The data were obtained with the SPRAT spectrograph of the Liverpool Telescope, La Palma, on the night of 2017 January 09 with a resolution R=350 and a wavelength range of 400-800nm.

Our spectrum of iPTF17bv is noisy, but shows a possible Supernova Ic (post maximum) spectrum with z=0.039. The nearest host galaxy is 2MASX J08164468+4115597 with z=0.0385.

iPTF17ck shows a probable AGN/Galaxy spectrum with redshift z=0.121.  The nearest host is SDSS J074151.78+292114.1 (no redshift quoted).


DisclaimerNone

T. Kupfer (Caltech), R. Quimby (SDSU), S. M. Adams (Caltech), H. Vedantham
(Caltech), M. M. Kasliwal (Caltech)

report on behalf of the GROWTH (Global Relay of Observatories Watching
Transients Happen) and iPTF (intermediate Palomar Transient Factory)
collaborations

We report the spectroscopic follow-up observations on ATLAS17aeu (Tonry et
al. LVC GCN #20382
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 ) and iPTF17cw (Kasliwal et al. LVC GCN #20398
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 ) using the
Double Beam spectrograph (DBSP) on the Palomar 200-inch telescope. The
position of both targets are within the probability contour of LIGO/Virgo
G268556 (LVC, GCN #20364
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 ).  All observations were obtained on 2017 Jan 7 UT
under poor weather conditions with a partly cloudy sky. Classifications
were performed using Superfit (Howell et al. 2005, ApJ, 634, 1190).

ATLAS17aeu was observed on 2017-01-07.5 UT with a total exposure time of 60
min resulting in a signal to noise ratio ~1.5 in the continuum. No obvious
emission or absorption lines are detected in the spectrum. To search for
features from a Galactic source at z=0, we set a 3-sigma flux limit around
6563 Angstrom of 3.3e-17 ergs/s/cm^2/A. This result is consistent with
Chambers et al. (LVC GCN #20407
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 ) who reported a featureless spectrum of
ATLAS17aeu obtained with Gemini.

iPTF17cw was observed on 2017-01-07.55 with a total exposure time of 20 min
which results in a signal to noise ratio ~11 in the continuum. The spectrum
shows a blue continuum peaking around 3850 Angstroem (rest frame) with
weak, broad features. We found a good match of the spectrum with the
SNIc-BL SN1998bw pre-maximum at z=0.093. The redshift is consistent with
the photoz=0.101��0.0279 derived by SDSS for the host Galaxy.

D. Xu (NAOC/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G.
Ma, T.Z. Yang, F.F. Song (XAO), X. Zhou, T.M. Zhang (NAOC/CAS), H.B.
Zhao, B. Li, G.T. Zhaori (PMO), J.M. Bai, J.R. Mao (YNAO) report on
behalf of a Chinese Gravitational Wave collaboration:

We have performed tiled observations of LIGO/Virgo G268556 (LVC, GCN
20364
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 ) using the Nanshan One-meter Wide field Telescope (NOWT),
Xinjiang, China, the 0.6/0.9-m Schmidt telescope at Xinglong, Hebei,
China, and the 1-m telescope at Xuyi, Jiangsu, China.

The Nanshan 1-m has a FOV of 1.3x1.3 deg^2, and covered the position of
ATLAS17aeu (Tonry et al. GCN 20382
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 ), the potential optical afterglow of
GRB 170105A (e.g., Marcinkowski et al., GCN 20387
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 ; Sharma et al., GCN
20389
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 ; Kasliwal, et al., GCN 20393
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 ), in a single night. We obtained an
upper limit of m(V)>20.0 mag (3 sigma) at 14:55 UT on 2017-01-07.

The 0.6/0.9-m Schmidt telescope has a FOV of  1.5x1.5 deg^2, and covered
the position of ATLAS17aeu also in a single night. We obtained an upper
limit of m(White)>18.8 mag (5 sigma) at 18:26 UT on 2017-01-08.

The Xuyi 1-m has a FOV of 3.0x3.0 deg^2, and covered the position of
ATLAS17aeu in a single night. We obtained an upper limit of m(r)>14 mag
(3 sigma) at  14:32 UT on 2017-01-09.

In addition, we note that the two sources, dubbed EWE001 and EWE002, in
GCN 20394
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 , are obviously known sources in several surveys such as DSS II
and SDSS.





--
N: Jinzhong Liu, Dr.
O: Main building, 213
P: 150, Science 1-Street, Urumqi, Xinjiang 830011, China
T: 86 991 3689027
D: 2012-07-14
E: optics@xao.ac.cn

A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), E. Palazzi (INAF-IASF Bo), A. Rossi (INAF-IASF Bo), E. Cappellaro (INAF-OAPD), S. Covino (INAF-OAB), V. D'Elia (INAF-ASDC), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), L. Tomasella (INAF-OAPD), S. Yang (INAF-OAPD), L. Di Fabrizio, G. Mainella (INAF/TNG), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report:

We observed the position of the transient ATLAS17aeu (Tonry et al., LVC Circ. 20382) with the TNG 3.6m telescope located in Canary Islands equipped with the DOLORES camera in imaging mode. Observations consisted in 8x120s exposures in the I-band.

The transient is clearly detected with a magnitude I = 22.5 +/- 0.3 (Vega) at a mid time of 02:14:12 UT on 2017 Jan 8.

[GCN OPS NOTE(10jan17):  Per author's request, the time in the last sentence
was changed from 14:12" to "02:14:12".]

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G.
Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),
V.D'Elia (ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall
(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien
(GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A.
Melandri (INAF-OAB), B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R.
Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U.
Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M.
Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti
(INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja
(NASA/GSFC/UMCP) report on behalf of the Swift team:

Swift has continued to observed ATLAS17aeu (Tonry et al., LVC Circ.
20382), gathering a total of 21.3 ks of data, from T0+222 ks to T0+470
ks (where T0 is the GW trigger time). The X-ray counterpart (Evans et
al., LVC Circ. 20390) is now confirmed to be fading.

Assuming the trigger time from the GW event (LVC Circ. 20364) the light
curve is decaying with a power-law index of 2.2 (+1.1, -1.2). If instead
we take T0 from GRB 170105A (Marcinkowski et al., GCN Circ. 20387
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 ), the
decay index is 1.7 (+1.1, -0.9). At the mid-point of the latest 
observation, GW_T0+453 ks (=GRB_T0+381 ks) the 0.3-10 keV XRT count-rate
was 0.0017 (+/- 0.0006) ct/sec.

A spectrum compiled from the data can be fitted with an absorbed
power-law, with NH consistent with the Galactic value of 4.6e20 cm^-2
(Willingale et al. 2013) and photon index Gamma=1.60 (+0.4, -0.3).

Using this spectrum the count-rate above corresponds to an observed
(unabsorbed) 0.3-10 keV flux of (6.7+/-2.4)e-14  ( [7.2+/-2.6]e-14) erg
cm^-2 s^-1.

The spectral and temporal indices are consistent with the values
typically seen for X-ray GRB afterglows (e.g. the Swift-XRT GRB
catalogue: http://www.swift.ac.uk/xrt_live_cat/; Evans et al. 2009).

This circular is an official product of the Swift GW follow up team.

Varun Bhalerao (IUCAA), Sujay Mate (IUCAA), Dipankar Bhattacharya (IUCAA), Sukanta Bose (IUCAA), Gulab Chand Dewangan (IUCAA), Ranjeev Misra (IUCAA), Sanjit Mitra (IUCAA), A R Rao (TIFR), Tarun Souradeep (IUCAA), Santosh Vadawale (PRL), on behalf of the Astrosat CZTI team report:

Bhalerao et al. (GCN Circ. 20412
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 ) have used AstroSat CZTI to infer that GRB170105A is a long GRB, and have localised it to a  ~550 square degree region (1-sigma). This region includes 3.9% probability of containing the LIGO trigger G268556, based on the revised LALInference sky map (Greco et al,  20385). The overlap with the IPN triangulation (Svikin et al., GCN Circ. 20406
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 ) is about 50 square degrees.

The position of ATLAS17aeu (Tonry et al., GCN Circ. 20382
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 ) is marginally outside the AstroSat CZTI error region, consistent at better than 1.1 sigma. This further indicates that ATLAS17aeu is the afterglow of GRB170105A (Kasliwal et al., GCN Circ. 20393
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 ).

Liverpool Telescope Spectroscopy of iPTF-17bq and iPTF-17ee

I.A. Steele, A.S. Piascik, M.J.Darnley, C.M. Copperwheat (LJMU), M. M. Kasliwal (Caltech) and D. Perley (Dark Cosmology Centre, Copenhagen) report on behalf of a lager collaboration.

We report spectroscopy of the iPTF counterparts iPTF-17bq and iPTF-17ee.  The data were obtained with the SPRAT spectrograph of the Liverpool Telescope, La Palma, on the night of 2017 January 08 with a resolution R=350 and a wavelength range of 400-800nm.

In both cases the transient could not be clearly distinguished from the host galaxy in our spectra, which were obtained in poor (~2 arcsec) seeing.

iPTF17-bq shows a galaxy spectrum with redshift (SNID) z=0.059 and AGN-like emission lines.
iPTF17-ee shows a galaxy spectrum with redshift (SNID) z=0.085.


DisclaimerNone

S. J. Smartt, (QUB), K. W. Smith (QUB), M. E. Huber (IfA),
K. C. Chambers (IfA), D. R. Young, D. E. Wright (QUB), M. Coughlin
(Harvard), L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA),
A. Rest (STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs
(Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA)

Further to Chambers et al. GCN 20383
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 , we report that we covered 632
square degrees on the first night (beginning 57758.3) . We estimate
this corresponds to a probability of containing the source of 33%.  We
have since reduced this area to the higher probability central region,
recovering 357 sq degrees and a containment probability of 26% (based
on the LALInference map, GCN 20385
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 ).

Images were taken in the Pan-STARRS i-band in a series of overlapping
45s exposures, with typically 4-8 images at each position.  These were
combined into stacks and subtracted from the Pan-STARRS1 3Pi reference
image (Chambers et al. arXiv:1612.05560
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 , and available at
http://panstarrs.stsci.edu).

Using techniques discussed in Smartt et al. (2016, MNRAS, 462, 4094),
we have located and vetted transients with quality filters and a
machine learning algorithm on the images. We recover 6 iPTF objects
and 15 old transients known before the GW alert (given at the end for
completeness). ATLAS17aeu was recovered as discussed in Chambers et
al.  (GCN 20407
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 )

In the following table, we give our 55 targets, sorted by magnitude.  The
lightcurve trend is given (LC trend), indicating the change in
magnitude between earliest and latest MJD of detection. To select
these targets we required a minimum of 2 detections over 2 separate
nights.

Our area is completely within the SDSS DR12 footprint, and we give the
redshifts (p for photometric and s for spectroscopic) of the host
galaxies.  Objects with no obvious host are labelled "hostless".  Some
targets are coincident with faint sources in SDSS for which
star/galaxy separation and photo-z estimates are not reliable and we
note these.  We have removed obvious AGN and candidate AGN (low level
variability associated with galaxy cores), as well as stellar
variables.

In the comments we note iPTF coincidences (Singer et al. GCN 20401
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 ;
Kasliwal et al. GCN 20364
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 ). A small number of candidates have a low
real-bogus (RB) machine learning factor and should be treated with
caution. All have been scanned by human reviewers. 

The photometric redshifts from SDSS should not be used as a robust
filtering for distance (see discussion in Smartt et al. 2016), but we
provide them as a guide.

We are targeting the objects with changing lightcurves with
Gemini+GMOS.

Name 	RA	                 DEC          LC trend	  Earliest mjd	mag	         Latest mjd  z       Comment
PS17df	08:50:02.42	+46:39:48.8  fading 00.09 57758.43699	18.39	57759.4911  0.038 s iPTF17bo		
PS17fg	08:48:46.25	+44:00:24.6  fading 00.15 57758.42737	18.89	57761.4882  0.060 s iPTF17bq		
PS17fr	08:11:52.10	+25:25:21.4  rising 00.57 57758.43263	19.19	57761.4619  0.199 p iPTF17cf	
PS17fe	09:00:21.22	+63:50:49.8  fading 00.09 57758.39189	19.60	57759.4726  0.245 p	
PS17du	09:14:30.59	+54:28:34.4  fading 00.04 57758.42705	19.75	57759.4660  0.045 s 0.6" from core		
PS17dp	09:00:51.09	+45:26:44.3  rising 00.06 57758.39978	19.97	57759.5043  0.051 s 		
PS17gl	08:34:50.85	+61:13:02.2  rising 00.07 57758.39093	20.04	57759.4635  0.038 s 	
PS17ft	08:16:52.72	+26:27:25.3  fading 00.05 57758.44356	20.05	57761.4790  0.042 s 	
PS17fs	08:14:47.53	+27:50:12.2  fading 00.11 57758.45845	20.09	57761.4891  0.118 p iPTF17ch	
PS17bz	08:04:49.22	+29:19:48.8  fading 00.08 57758.40250	20.23	57761.4809  0.047 s 	
PS17fb	08:49:18.13	+44:38:31.1  rising 00.01 57758.41320	20.30	57759.4831  0.151 p	
PS17fh	07:55:14.13	+26:25:11.5  fading 00.14 57758.39608	20.32	57761.4492  0.119 p	
PS17fw	08:19:05.64	+23:20:42.8  fading 00.04 57758.40905	20.35	57761.4478  0.034 p	
PS17gb	08:21:17.00	+51:10:17.1  rising 00.13 57758.38839	20.36	57759.4635  0.197 p 	
PS17fa	08:47:22.51	+51:08:17.4  fading 00.02 57758.44371	20.41	57759.4865  0.497 p 	
PS17en	08:40:22.10	+38:43:25.0  fading 00.07 57758.44053	20.41	57761.4923  0.673 p iPTF17fa
PS17dy	08:13:00.78	+41:18:26.9  rising 00.00 57758.42812	20.43	57761.4760  0.282 p iPTF17fb	
PS17er	08:41:57.26	+40:55:07.7  rising 00.36 57758.45114	20.44	57761.4854  0.296 p 	
PS17fj	07:59:30.67	+28:27:03.8  fading 00.37 57758.41011	20.46	57761.4771  hostless 		
PS17fl	08:02:09.73	+28:49:44.7  rising 00.32 57758.42406	20.47	57761.4876  0.080 p	
PS17dw	07:49:25.36	+20:28:00.6  fading 00.05 57758.38695	20.48	57759.4846  0.171 p	
PS17fv	08:18:15.52	+43:45:03.4  fading 00.06 57758.45210	20.56	57761.5017  0.188 s
PS17gf	08:24:43.98	+35:29:45.8  rising 00.14 57758.46042	20.62	57761.4786  0.362 p 	
PS17gr	08:20:14.14	+27:13:44.2  fading 00.20 57759.47191	20.64	57761.4792  hostless 	
PS17gk	08:33:00.93	+38:51:04.7  fading 00.18 57758.43419	20.68	57761.4721  0.163 p	
PS17fy	08:19:47.91	+42:39:45.9  fading 00.09 57758.41450	20.73	57761.4678  0.166 p 	
PS17gv	08:54:41.22	+57:10:45.9  rising 00.08 57758.46079	20.82	57759.5027  0.076 p	
PS17gm	08:35:15.00	+48:27:06.2  fading 00.04 57758.44909	20.83	57759.4940  0.159 p 	
PS17fx	08:19:36.86	+48:06:38.9  fading 00.04 57758.42693	20.84	57759.4803  hostless		
PS17dk	08:55:48.76	+46:55:04.8  rising 00.10 57758.42465	20.85	57759.4746  0.567 p 	
PS17fp	08:06:52.00	+34:18:04.4  fading 00.22 57758.43602	20.85	57761.4726  0.193 p 	
PS17fm	08:02:26.56	+26:20:07.5  fading 00.05 57758.42467	20.85	57761.4661  hostless low RB factor		
PS17dj	08:54:13.87	+48:19:42.7  rising  00.05 57758.44299	20.86	57759.4844  0.382 p 		
PS17ea	08:30:11.01	+32:57:35.8  rising  00.32 57758.43602	20.88	57761.5046  0.110 p 	
PS17fn	08:05:51.40	+28:42:51.9  rising  00.59 57758.44882	20.88	57761.4973  0.072 p 	
PS17ga	08:20:47.13	+30:24:47.9  fading 00.03 57758.45271	20.90	57761.4895  r=22.35, faint source	
PS17fo	08:06:49.10	+28:16:05.9  rising  00.27 57758.44882	20.92	57761.4804  0.179 p 	
PS17gg	08:30:06.42	+48:28:34.4  fading 00.17 57758.43638	20.93	57759.4841  0.144 p  low RB factor	
PS17cj	08:10:23.04	+23:59:52.6  fading 00.10 57758.39319	20.94	57761.4614  r=22.9, faint source		
PS17dh	08:50:43.44	+56:42:44.0  rising  00.06 57758.43403	20.95	57759.4998  hostless  		
PS17fu	08:17:35.59	+47:05:06.3  rising  00.23 57758.41830	20.95	57761.4746  0.040 s		
PS17ei	08:37:00.85	+38:42:47.2  fading 00.01 57758.44228	20.98	57761.4775  hostless 		
PS17fz	08:19:57.24	+45:12:59.8  fading 00.17 57758.44267	21.14	57761.4625  0.175 p 	
PS17gj	08:32:56.15	+41:12:22.3  rising  00.08 57758.44494	21.17	57761.4882  0.276 p 		
PS17ec	08:35:47.59	+46:25:09.4  rising  00.11 57758.46003	21.24	57759.4855  0.403 p 	
PS17dx	08:05:30.92	+36:26:24.8  fading 00.08 57758.40284	21.33	57761.4500  hostless		
PS17dz	08:24:48.80	+30:53:37.3  fading 00.10 57759.48293	21.35	57761.4982  0.308 p 	
PS17el	08:39:41.07	+39:24:30.2  fading 00.03 57758.45160	21.37	57761.4788  hostless	
PS17gt	08:11:47.50	+37:44:39.4  rising  00.12 57759.47465	21.42	57761.4739  0.348 s		
PS17cw	08:38:37.02	+42:57:05.4  fading 00.12 57758.44623	21.46	57761.4923  0.35  p		
PS17gw	08:48:29.00	+43:24:48.4  rising  00.05 57759.47696	21.54	57761.4915  hostless 
PS17gd	08:23:08.94	+43:55:57.1  rising  00.06 57758.44611	21.56	57761.4711  r=22.4, faint source		
PS17b	08:23:44.47	+36:53:39.2  rising  00.15 57759.49179	21.62       57761.4837  0.224 p 
PS17gs	08:11:41.68	+38:28:22.4  fading 00.06 57759.47749	21.63	57761.4760  r=22.45, faint source 		
PS17gu	08:11:48.78	+37:18:50.3  fading 00.19 57759.46588	21.99	57761.4715  r=22,faint source		


This object was only detected on one night (we have no coverage of the
specific area afterwards), but has a high RB factor and is coincident
with a starforming galaxy. Hence it appears real, but we caution that
we do not have multiple night detections.

PS17co	08:13:46.29	+18:59:02.4  rising 00.02 57758.40522	18.30	57758.4070  0.124 s 	

The following transients were all recovered in our imaging, but were
discovered and reported well before G268556 was discovered.

AT2017M      08:23:09.79	+25:53:22.9 aka MLS150212-082310+255323	
AT2017N      08:25:42.74	+39:19:00.6		
PS1-14amh    07:55:40.63	+26:46:18.0	
SN2016hrv    08:33:21.92	+52:31:50.4	
ASASSN-16el  08:56:39.07	+52:06:08.0	
AT2016iyx
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     08:43:24.73	+37:32:45.8
AT2016jax
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     08:32:53.76	+42:08:01.6
SN2016gil    08:10:13.72	+33:57:25.6 
SN2016ins    08:07:27.35	+25:07:47.3
AT2016jau
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     08:00:40.94	+28:19:31.8
SN2016hqh    07:57:05.78	+23:08:55.2
AT2016jci
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     07:56:05.83	+28:22:35.3	
AT2016jay
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     09:21:43.35	+61:31:59.6	
AT2016hys
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     08:14:42.11	+38:24:08.5

A. J. Castro-Tirado, B.-B. Zhang, J. C. Tello, Y. Hu (IAA-CSIC, Granada), M. D. Caballero-Garcia (ASU-CAS), V. V. Sokolov, V. V. Vlasjuk, A. F. Valeev (SAO-RAS), E. Pian (SNS-Pisa), S. Jeong (SKKU), S. R. Oates (Warwick) and P. Pessev (GRANTECAN), on behalf of a larger collaboration, report:

We observed the transient iPTF17fs (Singer et al., LVC GCN 20401
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 ) with the 10.4m GTC telescope located at La Palma (Canary Islands, Spain) equipped with the OSIRIS spectrograph. The observations were carried out starting on Jan 9, 5:30 UT. The iPTF16fs spectra covering the range 3700-10000 A shows that this transient is a type Ia SN about 1 week before maximum at a redshift z~0.068.

We acknowledge excellent support from the GTC staff.

P. D'Avanzo (INAF-OAB), L. Tomasella, E. Cappellaro (INAF-OAPD), S. Piranomonte (INAF-OAR), A. Melandri (INAF-OAB), V. D'Elia (INAF-ASDC), G. Greco (Urbino University/INFN Firenze), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC),  E. Palazzi (INAF-IAFS Bo), A. Rossi (INAF-IASF Bo), S. Covino (INAF-OAB), L.Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR), L. Di Fabrizio, G. Mainella (INAF/TNG) on behalf of GRavitational Wave Inaf TeAm report:

We observed the transients iPTF17ck and iPTF17dz (Kasliwal et al., LVC GCN 20398
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 ) with the TNG 3.6m telescope located in Canary Islands equipped with the DOLORES camera in spectroscopic mode. The observations were carried out between 2017-01-09.1044 UT and 2017-01-09.1797 UT. The iPTF17ck spectrum is consistent with a Seyfert galaxy. We detect prominent emission features consistent with [OII], Hdelta, Hgamma, Hbeta, [OIII], Halpha at a common redshift z~0.122 (broadly consistent with the photometric redshift of this galaxy reported in SDSS-DR13: z=0.169 +/- 0.034). We cannot identify any contribution from the optical transient in the spectrum, nor in the acquisition image. 
The iPTF17dz spectrum shows that this transient is a normal SN of type Ia about 1 week before maximum at a redshift z~0.092 (that is smaller than the photometric redshift of this galaxy reported in SDSS-DR13: z=0.235 +/- 0.085).  The classification was performed using the GELATO (Harutyunyan et al. 2008, A&A, 488, 383)  and SNID (Blondin and Tonry 2007, ApJ, 666, 1024) tools. 

[GCN OPS NOTE(10jan17): Per author's request, all the SN name references were changed from '16' to '17'.]

K. C. Chambers (IfA), S. Smartt (QUB), J. Tonry, L. Denneau,
A. Heinze, B. Stalder, H. Weiland (IfA), C. W. Stubbs (Harvard),
K. W. Smith (QUB), T.-W. Chen (MPE), T. Kruehler (MPE), D. R. Young
(QUB), A. Rest (STScI), M. Coughlin (Harvard), M. E. Huber (IfA),
D. E. Wright (QUB), H. Flewelling, E. A. Magnier, A. S. B. Schultz,
C. Waters, R. J. Wainscoat (IfA)

Further to our discovery of ATLAS17aeu (Tonry et al. GCN 20382
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 ), we 
took a spectrum with Gemini-North + GMOS (R400 grating, 
4491-8778 Angs) on MJD = 57761.595. We also took an r-band image 
on the same night. 

The spectrum has a blue featureless continuum, with a signal-to-noise
in the continuum S/N~10 at 7000Angs.  There are no clear emission or
absorption lines visible that can anchor a redshift estimate.

The spectrum is not unlike some GRB afterglows as shown in the compilation
of Fynbo et al. 2009, ApJS 185, 526 
e.g. GRB060512, at z~2.1, GRB061110A (z=0.7578), GRB070129 (no z
estimate, but below z<3.4)

We report three more photometric points, two from Pan-STARRS1 and 
the other from Gemini+GMOS. 

MJD           Mag           Telescope 
57758.38159   18.18 0.04 i  Pan-STARRS1
57759.46468   20.90 0.12 i  Pan-STARRS1
57761.51968   22.77 0.17 r  Gemini+GMOS 

These data further support the hypothesis of Kasliwal et al. GCN 20393
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that this is most likely the afterglow of GRB170105A, supported by the
x-ray and radio detections of Evans et al. GCN 20390
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  and Corsi et al.
GCN 20396
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 .

Using the POLAR detection time, a temporal index of F_nu \propto
t**(-1.4) would be consistent with the photometry reported to date,
typical of GRB afterglows.

We note there are several other faint galaxies closer to ATLAS17aeu
than the brighter galaxy at z = 0.199 highlighted in Tonry et al. (GCN
20382
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 ). They have SDSS photometric redshifts of z ~ 0.35 - 0.38, but
are marginal detections in more than one band and therefore the 
photometric redshifts are uncertain.

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Tsvetkova,
A. Kozlova, and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:

The long-duration, soft-spectrum GRB 170105A was detected by POLAR 
(Marcinkowski et al., GCN Circ. 20387
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 ), AstroSat (CZTI; Sharma et al., 
GCN Circ. 20389
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 ), Konus-Wind, and INTEGRAL (SPI-ACS) at about 22447 s UT 
(06:14:07).

We have triangulated this GRB to a Konus-INTEGRAL annulus centered at 
RA(2000)=129.749 deg (08h 38m 60s)  Dec(2000)=+27.904 deg (+27d 54' 
14"), whose radius is 34.255(-14.832,+1.812) deg (3 sigma).

This localization may be improved.

The distance between the annulus center line and the ATLAS17aeu optical 
transient reported by Tonry et al. (LVC Circ. 20382) is 0.57 degrees, 
strengthening the association of the transient with the GRB initially 
suggested by Kasliwal et al. (LVC Circ. 20393).

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170105_T22450/IPN/.

As observed by Konus-Wind, the burst had a fluence of
2.56(-0.13,+0.18)x10^-6 erg/cm2,
and a 64-ms peak energy flux, measured from T0-0.204 s,
of 2.47(-0.30,+0.58)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170105_T22450/.

J.Y. Wei (NAOC), L.P. Xin (NAOC), X.M. Meng (NAOC), X.H. Han (NAOC),
N.Leroy (LAL), S. Antier (LAL), C. WU (NAOC), L. Huang (NAOC), Y. Xu
(NAOC), H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC),
J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), L. Jia (NAOC), S.C.
Zou(NAOC), S.F. Liu(NAOC), Q.C. Feng(NAOC), H.L. Li(NAOC), D.W. Xu (NAOC),
Y.J. Xiao (NAOC), W.L. Dong(NAOC), Y.T. Zheng(NAOC), E.W.Liang (GXU), X.G.
Wang(GXU), Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), S. Basa
(LAM), B.B. Wu (IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), C. Lachaud
(APC)  on behalf of the SVOM Gravitational Astronomy group report:



We took images on the location of two events of EWE001 and EWE002 (Liu et
al LVC Circ. 20382) with our GWAC_F60B (60cm) telescope, which is dedicated
to identify transient candidates found by GWAC (a part of ground instrument
of SVOM mission)  at Xinglong Observatory, China. Observation were obtained
in R band for 15 X 900s expoures during 16:49:29 and 22:02:03 (UTC) on
Juanary 8, 2017. The two events(objects) are corresponding to known objects
in USNO-B1.0 catalog.

-----------------------------------------------------------------------

EWE001: mag_R = 16.98   mag_R2(in USNO) = 15.35

EWE002: mag_R=16.77    mag_R2(in USNO) = 16.57

------------------------------------------------------------------------

The photometric uncertainty is ~ 5%. The comparison star is object with
mag_R2 =16.17 (09:13:19.611  61:05:44.13 J2000).

V.V.Bogomolov, S.I.Svertilov,
A.M.Amelushkin, V.O.Barinova, M.I.Panasyuk, A.V.Bogomolov, A.F.Iyudin,
V.V.Kalegaev, D.Nguen,  V.L. Petrov, I.V.Yashin, P.S.Kazarian, 
N.L.Dzhioeva,
Physics Department, Skobel`tsyn Institute of Nuclear Physics, Lomonosov
Moscow State University

V. Lipunov, E.S. Gorbovskoy, N.Tyurina, D.Kuvshinov, M.Panchenko
Lomonosov Moscow State University, Sternberg Astronomical Institute

I. Park, J. Lee, S. Jeong
Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, 
Suwonsi,
Korea

At event time for G268556 the detectors BDRG-1 and BDRG-2 on-board 
Lomonosov were directed  >60 degrees far from all regions present on LIGO 
probability map for G268556. BDRG-3 detector observed the southern high 
probability region directed to RA=25.8, Dec=-30.7. The Lomonosov satellite 
was located over South Africa at outer regions of SAA leading to high 
background. No burst-like events were observed, the 3 sigma upper limit 
for 1s-long GRB flux in 20-800 keV range is 2.5 cm-2*s-1.
The time intervals when the region of maximal probability of GW source was 
in BDRG FOV on 04.01.2017 from 9h to 13h are   9:07-9:27, 9:33-9:47, 
10:42-11:02, 11:07-11:24, 12:17-12:37, 12:42-12:59. No on-board 
GRB-triggers were generated at this time intervals.
BDRG on-board triggers were generated 4 times during the time period from 
10 hours before GW event to 10 hours after it  (at 02:33:17, 0 4:12:19, 
08:06:49 and 13:36:41).The significance of all these triggers do not 
exceed 9.5 sigma correspondent to the level of random events occurring ~10 
times per day. The  upper limit for 1s-GRB flux in 50-300 keV is 0.5 
cm-2*s-1 equivalent to 1e-7 erg/cm2 for typical GRB spectra.

  This message can be cited.

L. P. Singer (NASA/GSFC), T. Kupfer (Caltech), R. Roy (OKC),
M. M. Kasliwal (Caltech), S. B. Cenko (NASA/GSFC), and T. Barlow (Caltech)
report on behalf of the iPTF and GROWTH collaborations:

We continued our tiled observations of LIGO/Virgo G268556 (LVC, GCN 20364
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 )
using the Palomar 48-inch Oschin telescope (P48) on the night of
2017-01-08 UTC. Including our original observations on 2017-01-07
(Kasliwal et al., GCN 20398
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 ), we have now imaged 151 fields spanning 1069
square degrees, with a 51% chance of containing the true location of the
source.

Applying standard iPTF vetting procedures to the images taken on
2017-01-08, we flagged the following additional optical transient
candidates that had no previous history of detection or variability in
iPTF. We have listed the transients in order of priority for follow-up:

---------------------------------------------------------
  name      RA        Dec      time  mag    z    notes
---------------------------------------------------------
              No host or quiescent source
---------------------------------------------------------
iPTF17fs 162.900034 +69.833971 10:46 18.94
---------------------------------------------------------
         Coincident galaxy with unknown redshift
---------------------------------------------------------
iPTF17ha 230.580928 +80.725830 13:14 19.29
iPTF17gf 272.970627 +68.486958 13:32 20.03
iPTF17ft 201.323053 +78.426314 11:09 19.95
iPTF17fu 192.417627 +80.149750 11:11 18.78
iPTF17fw 156.366148 +71.757620 10:46 18.24
iPTF17gr 193.895770 +79.226903 11:11 20.21
iPTF17gv 176.227516 +82.619152 11:04 19.77
iPTF17hc 165.400920 +68.097753 10:47 19.52
---------------------------------------------------------
 Known redshift inconsistent with LIGO distance estimate
---------------------------------------------------------
iPTF17fe 330.745910 -03.303166 02:33 17.80 0.044
iPTF17fg 339.797294 -17.341041 02:49 16.63 0.074
iPTF17gw 178.409537 +72.864968 10:58 19.41 0.176 photo-z
iPTF17gj 257.427906 +70.158947 13:29 19.74 0.258 photo-z
---------------------------------------------------------
  Unresolved host or quiescent source, possibly stellar
---------------------------------------------------------
iPTF17he 214.716535 +79.793033 13:07 19.88
iPTF17ge 159.042893 +69.146836 10:47 19.87
iPTF17hf 195.818782 +80.173138 11:11 19.52
iPTF17hh 194.925476 +75.016124 11:08 20.34
iPTF17gu 194.101611 +78.204729 11:09 19.47
iPTF17gt 191.763759 +76.839773 11:09 19.70
iPTF17gs 199.058226 +76.521298 11:09 20.07
iPTF17hi 180.885869 +72.050360 10:58 20.30
iPTF17gn 232.045095 +74.611299 13:15 19.99
iPTF17gm 235.823172 +74.750334 13:15 19.69
iPTF17hd 213.248302 +79.332924 13:07 19.44
iPTF17gc 240.341194 +78.345723 13:17 19.54
---------------------------------------------------------

The known blazar NVSS J120651+772222 was excluded from this list.

Positions are stated in the ICRS. Times are in UTC. Magnitudes are based
on image subtraction; they are in the Mould R filter. Spectroscopic
redshifts of coincident galaxies are obtained from NED and photometric
redshifts from SDSS DR12.

We encourage further follow-up of the candidates above, especially of
iPTF17fs, for which no host galaxy or quiescent source was visible in
archival iPTF images. Observations of this source have been requested from
the GROWTH network (http://growth.caltech.edu).

S.R. Oates (Uni. of Warwick), A. A. Breeveld (MSSL-UCL), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), 
S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA), 
A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V.D'Elia(ASDC), P. Evans (U Leicester),
N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall (PSU), J. Kennea (PSU),
H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC),
D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Mingo (U. Leicester),  J.A. Nousek (PSU), P.T. O'Brien (U. Leicester),
J.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester),
D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),
M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift team:

The Swift/UVOT performed targetted observations of the field of ATLAS
transient ATLAS17aeu (Tonry et al., LVC Circ. 20382) from 00:00 UT to
01:35 UT on 2017 Jan 7 and again between 16:01 UT on 2017 Jan 7 to
01:30 on 2017 Jan 08. No optical afterglow consistent with the ATLAS
position or 'source5' of the XRT follow up of G268556 (Evans et al.,
GCN Circ. 20390
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 ) is detected in the UVOT exposures at more than 3 sigma.
We do note however a source at 2.9 sigma in the w2 filter, which in comparison
to the second observation appears to have faded.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the
exposures are:

Filter    T_start(UT)  T_stop(UT)  Exp(s)    Mag/3sigUL
v          7.007           7.009          144       > 19.1
v          7.667           7.936          1009      > 20.3

u          7.018           7.019          106      > 18.6
u          7.881           8.016          311       > 19.2

w1         7.014           7.018          290       > 19.5
w1         7.876           7.947          801       > 20.2

m2         7.009           7.014          435       > 20.0
m2         7.670           7.943          2413      > 21.2

w2         7.000           7.067          690       > 20.7   (20.76 +/- 0.37 detection at 2.9 sigma)
w2         7.658          8.069          5177      > 22.0   (22.41 +/- 0.53 detection at 2.1 sigma)

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the transient
(Schlegel et al. 1998).

[GCN OPS NOTE(08jan17): Per author's request, PE and JK were added
to the author list.]

T. Sakamoto, A. Yoshida, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of G268556 (GCN Circ. 20364
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 ).  No CGBM on-board trigger occurred at the time
of the event.  Based on the LIGO BAYESTAR localization sky map, the southern arc
of the high probability area was in the field-of-view of CGBM.  The summed LIGO
probabilities inside the HXM and the SGM field of view are 37% and 40%.

Based on the analysis of the light curve data with 0.125 sec time resolution
from -60 sec to 60 sec from the trigger time, we found no significant excess
around the trigger time in either the HXM (7-1000 keV) or the SGM (0.1-20 MeV)
data.

The CALET Calorimeter (CAL) was operating in high energy trigger mode at the trigger
time of G268556.  Using CAL data, we have searched for gamma-ray events above
10 GeV from -60 sec to +60 sec from the GW trigger time and found no candidates.
The summed LIGO probabilities inside the CAL field of view is ~30%, which
is largely overlapping with the HXM's FOV.

M. M. Kasliwal (Caltech), L. P. Singer (NASA/GSFC), E. Karamehmetoglu
(OKC),  S. B. Cenko (NASA/GSFC), R. Quimby (SDSU), D. Cook (Caltech), T.
Barlow (Caltech), V. Bhalerao (IUCAA), J. Rana (IUCAA), A. Goobar (OKC), J.
Sollerman (OKC), R. Amanullah (OKC), Y. Cao (UW Seattle), A. A. Miller
(Northwestern/Adler)

report on behalf of the iPTF and GROWTH collaborations:

We have performed tiled observations of LIGO/Virgo G268556 (LVC, GCN 20364
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 )
using the Palomar 48-inch Oschin telescope (P48). Due to weather, our
observations only began on 2017-01-07 UTC. The northern probability island
from the updated LALInference localization (LVC, GCN 20385
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 ) was observable
from Palomar for most of the night. Starting at 13:03 UT (2.88 d after the
LIGO trigger), we imaged 85 of the fields two or more times, spanning 622
square degrees. We estimate a 32% prior probability that these fields
contain the true location of the source.

During preliminary sifting through candidate variable sources using image
subtraction by both our IPAC pipeline (Masci et al. 2016) and NERSC
pipeline (Cao et al. 2016), and applying standard iPTF vetting procedures,
we flagged the following optical transient candidates for further follow-up:

  name       RA        Dec      time  mag    z     notes
-------- ---------- ---------- ----- ----- ------ ---------
iPTF17bo 132.510142 +46.663565 06:13 18.57 0.038   =ATLAS16ecj (GCN 20377
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 )
iPTF17bq 132.192751 +44.006807 06:11 19.11 0.054   spec-z
iPTF17bs 128.827313 +44.022911 06:11 20.35 0.049   photo-z
iPTF17bt 130.174781 +39.306960 06:08 20.05 0.1166  spec-z
iPTF17bu 124.471393 +40.726652 06:06 20.69 0.0608  spec-z
iPTF17bv 124.186115 +41.266753 06:06 19.23 0.039   spec-z
iPTF17cc 125.336819 +35.420771 06:00 20.06 0.064   spec-z
iPTF17ce 122.265555 +24.773640 05:55 20.19 0.350   photo-z
iPTF17cf 122.967123 +25.422642 05:55 19.06 0.199   photo-z
iPTF17ch 123.698029 +27.836746 05:53 20.22 0.118   photo-z
iPTF17ck 115.465769 +29.353904 07:08 19.18 0.169   photo-z
iPTF17cp 115.146554 +17.018280 07:05 19.90 0.072   spec-z
iPTF17cs 115.613615 +13.805968 07:03 19.48 0.066   photo-z
iPTF17cv 114.643374 +23.994179 07:01 20.60 0.081   photo-z
iPTF17dk 120.728531 +16.489364 07:21 20.00 0.069   photo-z
iPTF17dn 115.013574 +13.340217 09:11 19.08 0.037   photo-z
iPTF17du 114.886641 +10.661666 07:15 20.05 0.412   photo-z
iPTF17dz 126.106981 +24.997750 09:40 19.33 0.235   photo-z
iPTF17eb 118.169444 +10.174427 09:20 19.78 0.573   photo-z
iPTF17ec 111.440505 +17.716475 09:13 19.50         no redshift available
iPTF17ee 146.552954 +60.363235 10:07 19.15 0.102   possibly variable
iPTF17ef  117.10532 +20.863792 07:06 20.32 0.162   photo-z
iPTF17eh 116.453873  +9.318206 07:15 19.75 0.077   photo-z
iPTF17ei 114.113854 +25.736748 09:29 19.56 0.101   photo-z
iPTF17ej 116.903063 +25.599466 09:29 20.40 0.543   photo-z
iPTF17ep 137.758943 +62.963989 09:38 19.97 0.115   photo-z
iPTF17et  126.46248 +32.611008 07:30 19.46 0.124   spec-z
iPTF17ez 118.434093 +19.300562 07:14 20.19 0.538   photo-z
iPTF17fa 130.091957 +38.723745 06:08 19.94 0.673   photo-z
iPTF17fb 123.253486 +41.307429 06:06 20.38 0.282   photo-z
iPTF17fc 123.845936 +40.118490 06:04 19.78 0.067   photo-z

Some additional transients not listed above fell just outside the 90%
contour localization contour, e.g. iPTF17cw 135.909904 +43.097300.

Positions are stated in the ICRS. Times are in UTC. Magnitudes are based on
image subtraction; they are in the Mould R filter and in the AB system,
calibrated with respect to point sources in SDSS as described in Ofek et
al. 2012.

None of the above transients show prior history of detection in iPTF
archival images. All of the above transients coincide with a galaxy that is
visible in iPTF and/or SDSS images. Archival spectroscopic or photometric
redshifts of the transients' likely host galaxies are given above. Of the
transients, those that are most consistent with the directional distance
estimate from LIGO (e.g., |[galaxy distance] - [GW mean distance]| < 1.5 *
[GW distance std.
dev.]) are iPTF17ce, iPTF17ck, iPTF17dz, iPTF17ef, and iPTF17ei.

We encourage spectroscopic classification of these candidates.

A. Corsi (TTU), M.M. Kasliwal (CalTech), D.A. Frail (NRAO), and N.T. Palliyaguru (TTU) 
report:

We observed the position of the fast-fading ATLAS17aeu (Tonry et al. LVC GCN#20382
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 ) 
located in the error region of LIGO/Virgo G268556 (LVC GCN#20364
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 ) with the Karl G. 
Jansky Very Large Array (VLA) in its A configuration. The observations started on 
2017-Jan-07 14:06:40 UT, ended on 2017-Jan-07 15:06:29 UT, and were carried out in 
C-band (central frequency of about 6 GHz).

A provisional reduction of our data shows a radio source located at the position of 
ATLAS17aeu. For this source, we measure a radio flux of (159.0+/-9.8) uJy at 6.2 GHz. 
We note that the broad-band detection (radio, optical, and X-rays) of ATLAS17aeu is 
consistent with a GRB afterglow hypothesis (see Evans et al. LVC GCN#20390
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  and 
Kasliwal et al. LVC GCN#20393
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 ). 

Further observations are planned.

We thank the VLA staff for rapidly executing these observations.

M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Verrecchia (ASDC and
INAF/OAR), G. Minervini (INAF/IAPS), A. Giuliani (INAF/IASF-Mi), A.
Bulgarelli, A. Zoli (INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), I.
Donnarumma, P. Munar-Adrover, G. Piano (INAF/IAPS), F. Lucarelli (ASDC
and INAF/OAR), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), F. Longo (Univ.
Trieste and INFN Trieste), A. Ursi (INAF/IAPS), F. Fuschino (INAF/IASF-Bo),
Y. Evangelista (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen
University)(INAF/IAPS), A. Argan (INAF/IAPS),  M. Pilia, A. Trois
(INAF/OA-Cagliari), V. Fioretti (INAF/IASF-Bo), report on behalf of the
AGILE Team:

In response to the LIGO/Virgo GW trigger G268556 (Shawhan et al., GCN
#20364
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 ) we performed an analysis of the AGILE Gamma-Ray Imaging Detector
(GRID) data on different timescales. On LIGO trigger time (T0), the GRID
exposure covered about 40% of the LIGO localization region; this region
was observed with off-axis angles between 0 and 70 deg.

An analysis of the data in the energy range 30 MeV - 10 GeV was performed
on timescales from 2 to 1000 sec centered at T0.
Typical 3-sigma preliminary upper limits (UL) obtained within the
accessible G268556 localization region are reported below:

2.0e-06 erg cm^-2 s^-1 for integration time of 2s,
3.4e-08 erg cm^-2 s^-1 for integration time of 100s.

These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode.
Additional GRID data analysis on longer time intervals is in progress.

Liu, Jinzhong (XAO); Xu,dong (NAOC); Zhang, Yu (XAO); Zhang, Xuan (XAO); Niu, Hubiao (XAO); Pu, guangxin (XAO); Ma, shuguo (XAO); Yang, taozhi (XAO); Song, fangfang(XAO), on behalf of the NOWT group report:

We are following up the GraceDB event (event UID: G268556) with Nanshan One-meter Wide field Telescope (NOWT) from Xinjiang Astronomical observatory (XAO). V band with 180s is used during this survey observation, and the maximum probability northern-skymap (Submitted by GraceDB Processor on Jan 4, 2017 3:07:44 PM) with 100 square degree is covered.


By cross-certification using the UCAC3 catalogue, here we reported two new transients close to Tonry et al., (LVC Circ. 20382) with 35", which were named as EWE001 and EWE002.

EWE001: HJD               RA(Deg.)         DEC(Deg.)      V_mag       M_err    
        2457761.12729148  138.30136        61.098523      15.024      0.086

EWE001: HJD               RA(Deg.)         DEC(Deg.)      V_mag       M_err    
        2457761.12729148  138.32121        61.098307      14.090      0.039

 Analysis and survey are ongoing.




--
N: Jinzhong Liu, Dr.
O: Main building, 213
P: 150, Science 1-Street, Urumqi, Xinjiang 830011, China
T: 86 991 3689027
D: 2012-07-14
E: optics@xao.ac.cn

M. M. Kasliwal (Caltech), S. M. Adams (Caltech), H. Vedantham (Caltech), V.
Bhalerao (IUCAA), S. B. Cenko (NASA/GSFC), R. Quimby (SDSU)

report on behalf of the GROWTH (Global Relay of Observatories Watching
Transients Happen) and iPTF (intermediate Palomar Transient Factory)
collaborations

We observed the position of the fast-fading ATLAS17aeu (Tonry et al. LVC
GCN#20382
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 ) with the Large Format Camera on the Palomar 200-inch Hale
Telescope. At 2017-01-07 08:05:33 UTC, we found that ATLAS17aeu had faded
further to  i=21.9 +/- 0.3 mag (AB mags, calibration wrt SDSS).

If we fit a power law to the decay, the best-fit slope is 1.1 +/- 0.2  and
best-fit t_zero is 57758.322 +/- 0.043 (i.e. 21.5 hr after GW trigger, LVC
GCN#20364
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 ). We caution that we have not corrected for the filter
differences between ATLAS and LFC. Incidentally, this t_zero is consistent
with GRB070105A reported by POLAR (GCN#20387
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 ) and detected by ASTROSAT
(GCN#20389
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 ). The hypothesis that this is the afterglow of the GRB appears
consistent with the X-ray detection reported by Swift (Evans et al. LVC
GCN#20390
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 ).

V.M.  Lipunov, O.Gress, N.Tyurina, E. Gorbovskoy, V.G. Kornilov, 
P.Balanutsa, 
A.Kuznetsov, V.Shumkov, M.I.Panchenko Lomonosov Moscow State University, 
Sternberg Astronomical Institute

D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

N.M. Budnev, O. Gress, K. Ivanov
Irkutsk State University

V.Yurkov, Yu.Sergienko, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk


MASTER OT J105811.78+811432.6 discovery - BLA flare in GW170401 field

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 10h 58m 11.78s +81d 14m 32.6s on 2017-01-06.74507 UT.

The OT unfiltered magnitude is 16.1m (limit 19.4m).

The OT is seen in 11 images. There is no minor planet at this place.

We have reference image without OT on 2012-10-20.65339 UT with unfiltered 
magnitude limit 19.7m.

There is Blazar with gamma-ray counterpart in 0.57" ( 
http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=164.5490875+81.242377777778&-c.rs=5 
)

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/MASTEROTJ105811.78+811432.jpg

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G.
Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),
V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall
(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien
(GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A.
Melandri (INAF-OAB), B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R.
Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U.
Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M.
Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti
(INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja
(NASA/GSFC/UMCP) report on behalf of the Swift team:

Swift has performed a targetted observation of the interesting
transient ATLAS17aeu (Tonry et al., LVC Circ. 20382). The observations
ran from 00:00 UT to 01:37 UT on 2017 Jan 7, and contained 1.4 ks of
cleaned PC mode data.

A faint, uncatalouged X-ray source is found at RA, Dec = 138.3059,
+61.0919 degrees, which corresponds to:

RA (J2000):  09h 13m 13.42s
Dec (J2000): +61d 05' 30.8") 

with an uncertainty of 6.3 arcsec (radius, 90% confidence). This is
4.1" from the position of ATLAS17aeu, consitent with that object.

This source ("source5" of the XRT follow up of G268556) has a 0.3-10
keV count rate of 7.2 (+/-2.9) ��10^-3 ct s^-1, corresponding to a
0.3-10 keV flux of 3.1 (+/-1.2) ��10^-13 erg cm^-2 s^-1, assuming a
power-law spectrum with Gamma=1.7 and NH=3e20 cm^-2. This is below the
upper limit derived from the RASS at the source location. This source
has not been previously observed by public XMM data, or Swift
observations.

At the present time we cannot ascertain whether the source is variable,
but follow up in encouraged.


A second, catalogued ("rank 4") source is also detected in our
observations. Details of both sources are below.

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 3 sources
==============

These are uncatalogued X-ray sources, however they are not brighter
than previous upper limits, so do not stand out as likely counterparts
to the GW trigger.
  
  Source 5:
  =============
    RA: 	 138.3059 ( = 09h 13m 13.42s) J2000
    Dec:	 +61.0919 ( = +61d 05' 30.8") J2000
    Error:	 +6.3 (arcsec, radius, 90% confidence).
    Peak Rate:	 7.2e-03 +/- 2.9e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 3.1e-13 +/- 1.2e-13 erg cm^-2 s^-1 (0.3-10 keV)
    RASS UL:	 1.8e-02 ct/sec, 3-sigma, converted to XRT (0.3-10 keV)

       so the source is not above the RASS 3-sigma upper limit.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 4:
  =============
    RA: 	 138.0838 ( = 09h 12m 20.11s) J2000
    Dec:	 +60.9299 ( = +60d 55' 47.6") J2000
    Error:	 +5.1 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.6e-02 +/- 4.4e-03 ct/sec (0.3-10 keV)
    Peak Flux:	 6.7e-13 +/- 1.9e-13 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J091222.2+605603 in the ROSAT/RASSFSC catalogue
    Separation:  22.1" from the XRT source
    Cat Rate:	 2.5e-02 +/- 9.4e-03 ct/sec 
    Cat Flux:	 7.1e-13 +/- 2.6e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy
      which is consistent (within 3-sigma) with the distance to the GW
object.
    A SIMBAD object `2MASS J09122029+6055503' is 3.1" away.
    There is 1 2MASS object within the source's 3-sigma error radius.

This circular is an official product of the Swift team.

D. Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D. Galloway, E.Rol, E.Thrane (Monash U.), V. Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney (U. Sheffield), G. Ramsay (Armagh O.), P. O'Brien, R. Starling (U. Leicester)

On behalf of the GOTO collaboration:

We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to GCN #20364
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 . Targeted observations containing ~45% of the BAYESTAR source location probability were performed between 21:47 UT Jan 4 2017 and 06:20 UT Jan 5 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 20 and 35 times during that observing window. These regions were also observed as part of a survey mode program the night before with 2x30s exposures at each position between 4:37 and 6:35 UT Jan 4 2017 (4-6 hours before the event). Considering the updated LALInference map (GCN #20385
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 ), our pointings cover 40% of the total probability.

Conditions were not photometric with some variable thin clouds present. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing. Analysis is ongoing and notable source detections will be reported in a future circular.

M. Berton, G. La Mura, S. Chen (DFA-UNiPd), L. Tomasella, E. Cappellaro (INAF-OAPD), A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), G. Greco (Urbino University/INFN Firenze), P. D'Avanzo (INAF-OAB), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), V. D�Elia (INAF-ASDC),  E. Palazzi (INAF-IAFS Bo), A. Rossi (INAF-IASF Bo), S. Covino (INAF-OAB), L.Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report:

The transient MASTER OT J090021.21+635049.7 (GCN 20381
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 ) was observed with the Asiago 1.82m Copernico telescope equipped with the AFOSC camera on 2017-01-06.883 UT. The noisy spectrum shows a broad P-Cygni like feature with the absorption centred at 674nm. The best fit with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) is with a type Ia SN near maximum at a redshift ~0.10. The transient has an apparent magnitude V~19.4, that would indicate an absolute magnitude -18.9, fully consistent with the spectroscopic classification.

However, we notice that this is inconsistent with the photometric redshift of the host galaxy listed in SDSS-DR13 (z=0.245).

We also obtained a 15 min r-band exposure centred on the unusual transient ATLAS17aeu 09:13:13.89 +61:05:33.6 (GCN20382
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 ) on 2017-01-06.913 UT. No source was detected with an upper limit r~21.7 (2.5 sigma).

The LIGO Scientific Collaboration and Virgo report:

We have re-analyzed LIGO data around the time of the compact binary
coalescence (CBC) event candidate G268556 (GCN 20364
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 ) taking into account
our current understanding of calibration uncertainties.  Although a full
recalibration remains to be done, we expect that this event will be
confirmed with a false alarm rate (FAR) of less than 1 per 100 years.

Parameter estimation has been performed using LALInference (Veitch et al.,
PRD 91, 042003) and a new sky map, LALInference_skymap.fits.gz, is
available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/events/G268556

This is the preferred sky map at this time.  This map has two arcs in
nearly the same positions as the original BAYESTAR sky map but the
probability is divided more equally between the northern and southern
arcs.  The 50% and 90% credible regions span about 500 deg2 and 2000 deg2,
respectively, which are somewhat larger than the initial BAYESTAR sky map
due to marginalizing over calibration uncertainties.

We will recalculate the sky map once the full recalibration is complete
and will share it at that time, but that is likely at least a few weeks
away.

J. Wood (UW-Madison) and I. Martinez (UMD)
report on behalf of the HAWC Collaboration:

The northern portion of the reported LIGO error region was within the HAWC field-of-view at the time of LVC trigger G268556. HAWC was operating and our real-time all-sky GRB monitoring analysis was running at this time. This analysis searches for excess counts over the steady-state cosmic-ray background using 4 sliding time windows (0.1, 1, 10, and 100 seconds) shifted forward in time by 10% their width over the course of the entire day. Within each time window, we search the HAWC sky within 50 degrees of zenith using 2.1 deg x 2.1 deg square bins shifted by ~0.1 deg along the directions of Right Ascension and Declination. This analysis is tuned for detecting ~100 GeV photons and is sensitive to the most fluent GRBs. It did not report any significant post-trials events near the time of gravitational-wave trigger G268556.

On 2017/01/05 we went back and re-analyzed the data within +/- 60 seconds of gravitational-wave trigger G268556 on 3 timescales (1, 10, 100 sec) to look for excesses consistent with the latest LIGO map. None were found.

As a complementary analysis we integrated the ~2 hours following the trigger time. This corresponds to the time interval when the searched region (90% probability contour) stayed in our field-of-view. The analysis performed on this data set is sensitive to ~0.5-100TeV. We found no significant excess.

HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico that monitors 2/3 of the sky every day with an instantaneous field of view of ~2 sr.

K. C. Chambers (IfA), K. W. Smith (QUB), M. E. Huber (IfA),
S. J. Smartt, D. R. Young, D. E. Wright (QUB), M. Coughlin (Harvard),
L. Denneau, H. Flewelling, A. Heinze, E. A. Magnier (IfA), A. Rest
(STScI), B. Stalder (IfA), A. S. B. Schultz, C. W. Stubbs (Harvard)
J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland (IfA) 

We report observations of the localisation skymap for LIGO/Virgo
G268556 with the Pan-STARRS1 telescope (see Chambers et
al. arXiv:1612.05560
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 ) and our search for transients (Smartt et
al. 2016, MNRAS, 462, 4094).
 
The alert for G268556 came too close to sunrise for immediate
observations at the time of the event release and we started observing
the LIGO/VIRGO localisation region at 57758.309 (2017-01-05 07:34:57
UT), beginning at RA=114 DEC=+5 and scanning the error lobe
north and eastwards to approximately R=140, DEC=+65.
A plot of the footprints has been uploaded to GraceDB. 

The images were taken in the Pan-STARRS i-band in a series of
overlapping 45s exposures, with typically 4 images at each position.
These were combined into stacks and subtracted from the Pan-STARRS1
3Pi reference image (as discussed in Chambers et al. arXiv:1612.05560
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 ,
and available at http://panstarrs.stsci.edu). The combined images typically 
reach i~21. 

We have located several tens of transient candidates and will report these in
a GCN after a further nights observing on 57759, and confirmation of
stationary sources.

J. Tonry, L. Denneau, A. Heinze, B. Stalder, H. Weiland (IfA),
C. W. Stubbs (Harvard), K. W. Smith, S. J. Smartt, (QUB), D. R. Young
(QUB), A. Rest (STScI), K. C. Chambers (IfA), M. Coughlin (Harvard),
M. E. Huber (IfA), D. E. Wright (QUB), H. Flewelling, E. A. Magnier,
A. S. B. Schultz, C. Waters, R. J. Wainscoat (IfA)

Following on from GCN 20377
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 , we have processed the ATLAS data
beginning at 57758.296 (2016-01-05.296 UT) which started at a pointing
centre of RA=80, DEC=-30, and moved north and east across the northern
sky lobe to RA=170,80.

We find one transient that appears to be new (and recovered old
ones). This object has some unusual characteristics that warrant
further attention

ATLAS17aeu 09:13:13.89 +61:05:33.6 (138.30789 +61.09267) J2000

The position is within the inner 16% probability contour.  This object
is not spatially coincident with any star or host galaxy.

The lightcurve faded by 0.85 mag over 1.176hrs  

  MJD           c mag  err 
 57758.4129676  18.05 0.09   
 57758.4144595  18.18 0.1    
 57758.4267173  18.22 0.1    
 57758.4419066  18.58 0.13   
 57758.4469072  18.45 0.11   
 57758.4479226  18.34 0.11   
 57758.454986   18.39 0.11   
 57758.4619614  18.90 0.18   

(the cyan mag is effectively an average of g and r). 

The object has now fallen below the detection limit (orange filter; 
o ~ 19) on the night of 57759. 

Such a fast fade is unusual if the object is extragalactic. 

The obvious immediate explanations for this object are 
1) It is not a real astrophysical transient. We consider this unlikely. 
2) The photometric errors are under-estimated and it is flat. We consider
this unlikely, and the errors to be reliable. 
3) It is a Galactic CV. But the fading is too fast for typical CVs.
4) It is an M-dwarf flare. But the fading is slow for a typical
M-dwarf (which are usually between 2 and >5 mags per hour)

We note that there is no faint point source in the Pan-STARRS 3Pi
stacked sky (Chambers et al. 2017, arXiv:1612.05560
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 , and
http://panstarrs.stsci.edu).  There is no counterpart in the MPC,
Vizier, WISE, various CV and stellar catalogues.

The object is 23 arcsec from the galaxy SDSS J091312.36+610554.2 which
has a spectroscopic redshift of z = 0.199 +/- 0.00004.  This implies a
luminosity distance of 990 Mpc (for Ho=69).  If ATLAS17aeu is related,
it would be at a projected distance of 75kpc from the Galaxy.

This luminosity distance is consistent with the BAYESTAR 3D volume
rendering (Singer et al. 2016, ApJ 829, L1) of G268556 which suggests
a 10-90 percentile probability of 520-1010 Mpc in this direction.

If it were associated with the z = 0.199 +/- 0.00004 galaxy, then it 
would be unusually luminous (M_g ~ -21.5). 

While a Galactic origin is still the most probable, it remains to be
confirmed. We encourage a search of any contemporaneous data taken at
the same time we detected this object and deep imaging of the position
to recover any host object (star or galaxy).

V.M.  Lipunov, N.Tyurina, E. Gorbovskoy, V.G. Kornilov, P.Balanutsa, 
A.Kuznetsov, V.Shumkov, M.I.Panchenko 
Lomonosov Moscow State University, Sternberg Astronomical Institute

D.Buckley, S. Potter, M. Kotze South African Astronomical Observatory

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

N.M. Budnev, O. Gress, K. Ivanov
Irkutsk State University

V.Yurkov, Yu.Sergienko, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk


Global MASTER Net was starting observations of the LIGO/Virgo G268556 
error field at 2017-01-04 15:46:07 UT during regular sky survey up to 20 
unfiltered magnitude.

After received alert circular (Shawhan et al.,20364) we started 
special inspection with 
MASTER-Amur, MASTER-Tunka, MASTER-Kislovodsk, MASTER-OAFA and MASTER-SAAO 
telescopes.  We cover 50.2% initial probability now up to 20.5 mag.


The first OT  MASTER OT J090021.21+635049.7 detection ( Possible SN in 
1.797"  from Sloan galaxy).


MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) 
= 09h 00m 21.21s +63d 50m 49.7s on 2017-01-05.06666 UT.
The OT unfiltered magnitude is 18.6m+-0.2 (limit 19.9m).

The OT is seen in 4 image.

We have reference image without OT on 2012-10-20.91652 UT with unfiltered 
magnitude limit 19.7m.

No known minor planets, brighter than V = 21.0, were found in the 
15.0-arcminute region around R.A. = 09 00 21.21, Decl. = +63 50 49.7 
(J2000.0) on 2017 01 05.07 UT .

OT is offset  1.79709" from the Sloan galaxy rmag=19.96, gmag=20.64 
http://skyserver.sdss.org/dr9/en/tools/chart/navi.asp?ra=135.08928453&dec=63.84745156

Spectral and photometrical observations are required .

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/090021.21635049.7.png

J. Tonry, L. Denneau, A. Heinze, B. Stalder,  H. Weiland (IfA), C. W. Stubbs (Harvard), 
K. W. Smith, S. J. Smartt, (QUB), D. R. Young (QUB),  A. Rest (STScI),   
K. C. Chambers (IfA), M. Coughlin (Harvard), M. E. Huber (IfA), D. E. Wright (QUB), 
H. Flewelling,  E. A. Magnier,  A. S. B. Schultz,   C. Waters, R. J. Wainscoat (IfA) 

We report the following observations of the skymap for LIGO/Virgo
G268556 with the ATLAS telescope system ATLAS is a twin 0.5m telescope
system on Haleakala and Mauna Loa (see Tonry et al. ATel 8680 and
Tonry 2011, PASP, 123, 58). The first unit is operational on Haleakala
and is robotically surveying the sky in two filters cyan and orange
(denoted c and o, all mags are in AB system). More information is on
http://www.fallingstar.com

The alert for G268556 was received 6.5 hours after the event, too
close to sunrise for targeted observations on 57757 in Hawaii. The
next night we started observing the LIGO/VIRGO localisation region at
57758.296 (2016-01-05.296 UT) starting at a pointing centre of RA=80,
DEC=-30, moving north and east across the lobe to RA=170,80. A total
of 1250 square degrees were covered.  Sets of dithered 8x30sec
exposures in the cyan filter were taken, at a 5-sigma sensitivity of c
= 19.0 for each exposure.  Difference images are automatically created
with a reference image built during early 2016. These data are currently 
being processed and results will be reported soon. Maps will be 
uploaded to GraceDB.

During the previous night (2016-01-04 UT) ATLAS did its routine survey
of a 20 degree wide declination strip between RA = 334 to 213 deg
(wrapped through 0), and DEC = +15 to +35 deg. This intersected a
small part of the LIGO/VIRGO map (containing 9% of the probability)
between 30mins to 3hrs after the detection time of G268556.  ATLAS
also surveyed this strip four days prior on 57753, but the sky was
partly cloudy. No obvious transient is visible in this 9% region.

Furthermore, ATLAS has been scanning the northern region containing
the highest probability contours during the last three weeks. We
report here bright transients found before the detection of G268556.
They will mostly be still visible on the sky map region, but are 
mostly field supernovae (or CVs) and unrelated to the GW source. 

IAU Name  | ATLAS Name | RA (J2000)  | Dec (J2000) | Disc. MJD | Disc. Date  | Disc Mag |  Notes
AT2016iyx
Loading...
 
  | ATLAS16dzp | 08:43:24.74 | +37:32:45.8 | 57742.47  | 20161220.47 |  17.28 o |        
SN2016izg | ATLAS16eak | 07:53:12.77 | +12:53:56.4 | 57736.47  | 20161214.47 |  17.10 o |  ASASSN-16pb (Ia)
AT2016izk
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  | ATLAS16eaw | 08:49:04.77 | +14:24:49.8 | 57744.57  | 20161222.57 |  16.62 c |   ASASSN-16pc (CV)
AT2016jae
Loading...
 
  | ATLAS16eay | 09:42:34.50 | +10:59:35.3 | 57744.61  | 20161222.61 |  17.42 c |     
AT2016jax
Loading...
 
  | ATLAS16ecb | 08:32:53.76 | +42:08:01.6 | 57746.49  | 20161224.49 |  17.60 c |     
AT2016jaw
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  | ATLAS16ecc | 08:48:21.88 | +24:31:51.9 | 57745.52  | 20161223.52 |  17.98 c |    
          | ATLAS16ecj | 08:50:02.45 | +46:39:49.0 | 57742.48  | 20161220.48 |  18.50 o |        |  
          | ATLAS17aay | 09:34:07.69 | +31:46:25.4 | 57745.55  | 20161223.55 |  18.44 c |        |

M. Soares-Santos (Fermilab), J. Annis (Fermilab), E. Berger (Harvard) D. J.
Brout (UPenn), R. Butler (Fermilab), H.-Y. Chen (UChicago), P.
Cowperthwaite (Harvard), H. T. Diehl (Fermilab), Z. Doctor (UChicago), B.
Farr (UChicago), D. Finley (Fermilab), R Foley, W-F Fong (Arizona), J.
Frieman (UChicago), M. Garcia-Belido (CIEMAT/Madrid), R. Gruendl (NCSA), K.
Herner (Fermilab), D. Holz (UChicago), R. Kessler (UChicago), E. Neilsen
(Fermilab), A. Palmese (UCL), M. Sako (UPenn), B. Yanny (Fermilab)

On behalf of the DECam GW follow-up team and the DESGW team:

We report on observations of LVC trigger G268556 conducted with the Dark
Energy camera (DECam) on the Blanco telescope at CTIO as part of NOAO
program 2016B-0124 (PI: Berger). The observations commenced on 2017-01-05
01:34:45 UT (15 hours following the GW detection), and consisted of 90-sec
exposures in i-band.

We observed about 10% of the localization probability map in 4h of
observing time, covering 230 sq. deg. to a 5-sigma point source limiting
magnitude of i~23 AB mag.

Coordinates are given below.

Analysis is underway.

radec
0.430246 -35.4841
358.640221 -34.45238
4.146646 -37.5131
14.386904 -42.5855
355.722346 -33.4384
2.265329 -36.4986
16.634896 -43.5999
355.386617 -31.41045
6.077717 -38.5275
353.648446 -32.42443
0.096254 -37.5131
357.452083 -32.42443
12.230792 -39.542
12.212492 -41.571
358.27245 -36.48033
18.7554 -42.5855
8.062783 -39.542
1.970025 -38.5275
16.510696 -41.571
10.106204 -40.5565
18.962325 -44.6144
5.874796 -40.5565
10.018408 -42.5855
12.1923 -43.5999
14.3376 -40.5565
3.894796 -39.542
21.375646 -45.6289
21.375646 -45.6289
4.374242 -35.4841
21.0774 -43.5999
10.185421 -38.5275
7.914283 -41.571
2.53245 -34.4696
23.482921 -44.6144
14.441625 -44.6144
25.97865 -45.6289
23.882129 -46.6434
8.196946 -37.5131
6.261133 -36.4986
16.772746 -45.6289
18.568996 -40.5565
16.398796 -39.542
53.652854 -47.6579
25.519996 -43.5999
32.378042 -46.6434
19.192333 -46.6434
55.827133 -46.6434
20.808883 -41.571
27.492404 -42.5855
29.962592 -43.5999
28.003529 -44.6144
58.434467 -47.6579
30.305954 -45.6289
28.572029 -46.6434
36.758192 -48.6723
37.067833 -46.6434
33.226408 -42.5855
39.308158 -47.6579
57.923654 -45.6289
60.517033 -46.6434
48.871258 -47.6579
34.908854 -45.6289
29.744954 -47.6579
23.123908 -42.5855
25.107092 -41.571
51.137342 -46.6434
53.32065 -45.6289
46.447529 -46.6434
46.5153 -48.6723
59.948521 -44.6144
51.3939 -48.6723
34.526567 -47.6579
31.879696 -48.6723
26.489458 -47.6579
32.824725 -44.6144
60.393646 -37.5131
44.089667 -47.6579


-- 
Marcelle Soares-Santos
http://home.fnal.gov/~marcelle/
http://www.darkenergysurvey.org/ <http://darkenergysurvey.org/>

M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Ursi (INAF/IAPS),
F. Fuschino (INAF/IASF-Bo), Y. Evangelista, I. Donnarumma (INAF/IAPS),
F. Verrecchia (ASDC and INAF/OAR), G. Minervini (INAF/IAPS), M. Marisaldi
(INAF/IASF-Bo and Bergen University), A. Bulgarelli, A. Zoli
(INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR), G. Piano,
P. Munar-Adrover, A. Argan (INAF/IAPS), M. Cardillo (INAF/OA-Arcetri and
INAF/IAPS), A. Giuliani (INAF/IASF-Mi), M. Pilia, A. Trois
(INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste) report on
behalf of the AGILE Team:

In response to the LIGO/Virgo GW event G268556 at T0 = 2017-01-04
10:11:58.599 UTC, a preliminary analysis of the AGILE-GW data processing
procedure identified a Mini-Calorimeter (MCAL) data acquisition within
the time interval close to T0. The MCAL full telemetry acquisition
(following an internal trigger) started at T1 = 10:11:47.397 UTC and
ended at T2 = 10:11:59.997 UTC. The acquisition lasted 12.6 sec and
included the T0 time of interest. An analysis of these data does not
reveal any significant transient event in the energy range 0.4-100 MeV.
Three-sigma upper limits (UL) are obtained for a 1 s integration time at
different celestial positions within the accessible G268556 localization
region, from a minimum of 5.45e-7 erg cm^-2 to a maximum of 6.18e-7 erg
cm^-2, in the 400-10000 keV energy range. The AGILE-MCAL detector has a
full solid angle acceptance, and is operational in the range 0.4 - 100
MeV. The MCAL current trigger rate is on average ~ 0.15 every 20 sec.

The Super-Agile (SA) detector had a partial coverage of the G268556
localization region at T0 (within 1s), that was observed between 0 and
30 deg off-axis. No significant detection was obtained in the SA light
curve (20-60 keV), for a stable background within +/-100s from T0. The
3-sigma UL has been derived for a 1 s integration time, and varies between
1.5e-8 erg cm^-2 (for an on-axis position) and 6.6e-8 erg cm^-2 (for a 30
degrees off-axis position). SA is an X-ray coded mask instrument with
40x40 deg field of view at half-sensitivity.

Furthermore, a search in the AGILE anticoincidence (AC) and GRID
ratemeters data did not produce any significant detection.

The GRID large-FoV (2.5 sr) imaging instrument had exposure near T0 for a
significant fraction of the G268556 localization region. The GRID data
analysis in the energy range 30 MeV - 10 GeV is in progress, and the
results will be reported in a following GCN.

Giacomo Vianello (Stanford), Daniel Kocevski (NASA/MSFC), Francesco Longo
(Trieste University and INFN/Trieste), Julie McEnery (NASA/GSFC), Jeremy S.
Perkins (NASA/GSFC) and Judy Racusin (NASA/GSFC) report on behalf of
the Fermi-LAT team:

We have searched data collected by the Fermi Large Area Telescope (LAT) for
possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal
coincidence with the LIGO/Virgo trigger G268556.

Fermi/LAT had an instantaneous coverage of ~55% at the time of the trigger
(T0 =  2017-01-04 10:11:59 UTC), and reached 100% cumulative coverage
within 5 ks. We define "instantaneous coverage" as the integral over the
region of the LIGO probability map that is within the LAT field of view at
a given time, and "cumulative coverage" as the integral of the
instantaneous coverage over time.

We performed a search for a transient counterpart within the 90% contour of
the LIGO Bayestar map on the time window from T0  to T0 + 10 ks and found
no significant excess.

The Fermi-LAT is a pair conversion telescope designed to cover the energy
band from 20 MeV to greater than 300 GeV. It is the product of an
international collaboration between NASA and DOE in the U.S. and many
scientific institutions across France, Italy, Japan and Sweden.

S.Karpov, G.Beskin (SAO RAS and Kazan Federal University,
Russia), S.Bondar, E.Ivanov, E.Katkova, A.Perkov (OJS RPC PSI,
Russia), A.Biryukov (SAI MSU and Kazan Federal University,
Russia), V.Sasyuk (Kazan Federal University, Russia)

Following GCN #20364
Loading...
 
  on the possible GW event G258556, we observed part of
its sky localization region with Mini-MegaTORTORA nine-channel wide-field
monitoring system (located at Special Astrophysical Observatory near
Russian 6-m telescope) starting on 2017-01-04 18:32:48 UT (8.3 hours since
trigger) under moderate weather conditions.

The system field of view has been centered on RA, Dec = 136, 54 covering
roughly 900 square degrees simultaneously. This covers about 30% of the
probability in the BAYESTAR map.
Coverage map of all nine channels is shown at
http://mmt.favor2.info/scheduler/1416/lvc

Every channel acquired 10 x 60s exposure images in white light between
2017-01-04 18:32:48 UT and 2017-01-04 18:41:50 UT. The footprints of
acquired images are uploaded to GraceDB.

Quick-look analysis did not reveal any transient brighter than V~14.5
magnitude in the data.

P.A. Evans (U. Leicester), J.A. Kennea (PSU), S.D. Barthelmy
(NASA/GSFC), A.P. Beardmore (U. Leicester), A.A. Breeveld (UCL-MSSL),
D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC), G.
Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),
V.D'Elia(ASDC), N. Gehrels (NASA/GSFC), P. Giommi (ASI), C. Gronwall
(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien
(GSFC/UMBC), D. Malesani (DARK/NBI), F.E. Marshall (NASA/GSFC), A.
Melandri (INAF-OAB), B. Mingo (U. Leicester),  J.A. Nousek (PSU), S.R.
Oates (U. Warwick), P.T. O'Brien (U. Leicester), J.P. Osborne (U.
Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester), D.M.
Palmer (LANL), M. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti
(INAF-OAB/PSU), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja
(NASA/GSFC/UMCP) report on behalf of the Swift team:

Swift has performed a series of 291 observations of galaxies (from the
GWGC catalogue) within the LVC error region for the GW trigger G268556,
using the 'bayestar' GW localisation map. The observations currently
span from 50 ks to 86 ks after the LVC trigger, and cover 31.3 sq
degrees on the sky (corrected for overlaps). This covers 0.047 of the
probability in the LVC skymap, and 0.051 of the probability in the LVC
map after weighting by galaxies in the GWGC catalogue.

We have detected 3 X-ray sources. Each source is assigned a rank of 1-4
which describes how likely it is to be related to the GW trigger, with
1 being the most likely and 4 being the least likely. The ranks are
described at http://www.swift.ac.uk/ranks.php.

We have found:

  * 0 sources of rank 1
  * 0 sources of rank 2
  * 0 sources of rank 3
  * 3 sources of rank 4

For all flux conversions and comparisons with catalogues and upper
limits from other missions, we assumed a power-law spectrum with
NH=3e20 cm^2, and photon index (Gamma)=1.7


RANK 4 sources
==============

These are catalogued X-ray sources, showing no signs of outburst
compared to previous observations, so they are not likely to be related
to the GW trigger.
  
  Source 1:
  =============
    RA: 	 133.0839 ( = 08h 52m 20.14s) J2000
    Dec:	 +47.5827 ( = +47d 34' 57.7") J2000
    Error:	 +5.4 (arcsec, radius, 90% confidence).
    Peak Rate:	 1.8e-01 +/- 6.7e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 7.9e-12 +/- 2.9e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J085218.0+473456 in the ROSAT/RASSBSC catalogue
    Separation:  21.8" from the XRT source
    Cat Rate:	 6.9e-02 +/- 1.4e-02 ct/sec 
    Cat Flux:	 1.9e-12 +/- 3.8e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 2.1-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy.
    A SIMBAD object `[VV2006] J085220.5+473458' is 3.1" away.
  
  Source 2:
  =============
    RA: 	 133.4418 ( = 08h 53m 46.03s) J2000
    Dec:	 +47.3117 ( = +47d 18' 42.1") J2000
    Error:	 +5.0 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.1e-01 +/- 6.8e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 9.1e-12 +/- 2.9e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  1RXS J085345.1+471847 in the ROSAT/RASSBSC catalogue
    Separation:  10.6" from the XRT source
    Cat Rate:	 1.8e-01 +/- 2.3e-02 ct/sec 
    Cat Flux:	 5.2e-12 +/- 6.5e-13 erg cm^-2 s^-1 (0.3-10 keV)
       so the source  is 1.3-sigma above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy.
    A SIMBAD object `BD+47  1620' is 2.8" away.
    There is 1 2MASS object within the source's 3-sigma error radius.
  
  Source 3:
  =============
    RA: 	 350.3156 ( = 23h 21m 15.74s) J2000
    Dec:	 -26.9822 ( = -26d 58' 55.9") J2000
    Error:	 +7.6 (arcsec, radius, 90% confidence).
    Peak Rate:	 2.6e-01 +/- 6.0e-02 ct/sec (0.3-10 keV)
    Peak Flux:	 1.1e-11 +/- 2.6e-12 erg cm^-2 s^-1 (0.3-10 keV)
    Cat Source:  2RXP J232115.1-265908 in the ROSAT/ROSPSPC catalogue
    Separation:  15.4" from the XRT source
    Cat Rate:	 1.9e+00 +/- 7.6e-02 ct/sec 
    Cat Flux:	 5.2e-11 +/- 2.1e-12 erg cm^-2 s^-1 (0.3-10 keV)
       so the source is not above the catalogued flux.
    There is no evidence for fading.
    NOTE: this source is NOT within 200 kpc of a GWGC or 2MPZ galaxy.
    NOTE: The source is close to a ~6 mag star (HR 8883) thus the X-ray
flux may be distorted by the presence of optical photons.

This circular is an official product of the Swift team.

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (APC/Universite Paris Diderot), D. Dornic (CPPM/CNRS), A. Kouchner (APC/Universite Paris Diderot), T. Pradier (IPHC/Universite de Strasbourg) report on behalf of the ANTARES Collaboration:

Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo G268556 event using the initial LIGO BAYESTAR probability map at event time. The ANTARES visibility at the time of the alert together with the 90% contour of the probability map are shown in: https://www.cppm.in2p3.fr/~dornic/events/G268556.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 50.6% chance that the GW emitter was in the ANTARES field of view.

ANTARES, being installed in the Mediterranean Deep Sea, is the largest neutrino detector in the Northern Hemisphere.  It is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range.  At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees.  In the range 1-100 TeV, ANTARES has the best sensitivity to a large fraction of the Southern sky.

No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G268556 event time.

An estimate of the upper limit on the associated neutrino fluence will be sent in a subsequent circular.

J.Y. Wei (NAOC), X.H. Han (NAOC), N.Leroy (LAL), C. WU (NAOC), S. Antier
(LAL),
L.P. Xin (NAOC), X.M. Meng (NAOC), L. Huang (NAOC), Y. Xu (NAOC),
H.B. Cai (NAOC), J. Wang (NAOC), X.M. Lu (NAOC), Y.L. Qiu (NAOC),
J.S. Deng (NAOC), L. Cao (NAOC), S. Wang (NAOC), E.W.Liang (GXU),
Y.G. Yang (HBNU), B. Cordier (CEA), S.N. Zhang (NAOC), S. Basa (LAM),
B.B. Wu (IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), C. Lachaud (APC)
on behalf of the SVOM Gravitational Astronomy group report:

We observed about 5600 square degree (14 sky regions) of the skymap of the
advanced  LIGO trigger G268556, with Mini-GWAC (Mini Ground Wide Angle
Camera), at Xinglong Observatory of NAOC equipped with U9000 camera
(FOV~400 square degree/camera). Mini-GWAC, as a part of ground instruments
of SVOM mission, comprises 12 wide field angle cameras (aperture=7cm),
working with unfiltered band. The observations are operated in time-series
mode, taking one exposure in 15 seconds (10s exposure + 5s readout). The
limit magnitude is ~12 mag in R band. We estimate a 84.4% prior probability
that these 14 regions contain the true location of the source.  The
coordinates of the 14 regions and observation time are list following:

Ra                 Dec            Camera_ID start-obs(UTC) end-obs(UTC)
Camera_ID  start-obs(UTC) end-obs(UTC)

07:46:49.578  +29:35:33.46  C1        12:30:41.1     13:49:41.5   C3
  19:14:39.9     21:17:22:8
07:48:54.239  +10:34:56.09  C2        12:30:41.1     13:49:49.5   C4
  19:14:39.9     21:17:36.8

09:10:51.599  +29:36:54.60  C1        13:50:29.3     15:14:52.1

09:12:54.096  +10:36:25.88  C2        13:50:29.3     15:14:44.2


10:34:57.404  +29:33:02.67  C1        15:15:28.4     16:22:20.7

10:36:57.072  +10:32:32.51  C2        15:15:28.4     16:22:07.9


09:17:21.644  +69:37:03.40  C1        19:14:27.3     22:39:37.7

09:21:25.794  +50:35:59.26  C2        19:14:27.3     22:39:25.3


11:52:01.006  +70:06:03.83  C3        16:21:28.7     17:57:31.9   C5
  19:14:32.9     22:39:31.9
12:02:07.741  +50:03:10.98  C4        16:22:17.5     17:57:30.2   C6
  19:14:32.9     22:39:25.2

06:34:42.357  +69:28:01.79  C5        14:55:58.2     17:57:22.7
06:40:16.529  +50:28:28.89  C6        14:56:10.4     17:57:35.7

14:34:10.239  +70:01:52.84  C7        19:14:55.3     22:39:18.3
14:44:41.102  +49:56:05.18  C8        19:14:55.3     22:39:21.9

Mini-GWAC is working in sky survey mode. The first image was taken 2 hours
20 minutes after event.  No any significant transient is found in our
online pipeline.
The image analysis is ongoing in detailed processing with our offline
pipeline. Further observations  of these fields are planned.

V. Savchenko and C. Ferrigno (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group: S. Mereghetti (IASF-Mi, Italy), E. Kuulkers (ESTEC/ESA, The Netherlands), A. Bazzano (IAPS-Roma, Italy), E. Bozzo, T. J.-L. Courvoisier (ISDC, University of Geneva, CH) S. Brandt (DTU - Denmark) R. Diehl (MPE-Garching, Germany) L. Hanlon (UCD, Ireland) P. Laurent (APC-CeA, France) A. Lutovinov (IKI, Russia) J.P. Roques (CESR, France) R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy)

We investigated serendipitous INTEGRAL observations carried out at the time of the LIGO/Virgo G268556. The satellite was pointing at RA = 00:04:02 Dec=+67:14:38, away from the high-probability region, derived from the LIGO Bayestar pipeline. The anti-coincidence shield of  spectrometer on board of INTEGRAL (SPI/ACS) covered the full LIGO 90% confidence region and provided the most stringent constraints on the flux of a possible electromagnetic counterparts in the energy range covered by INTEGRAL instruments. We investigated the SPI-ACS light curve between -100 and +100 s from the trigger time (2017-01-04 10:11:59 UTC) on temporal scales from 0.1 to 10 s and found no significant excesses over a very stable background. 

The SPI/ACS light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the incident angle. Assuming an optimal perpendicular direction of the burst to the INTEGRAL pointing direction, we estimate a 3-sigma upper limit corresponding to fluences of 1.6e-7 erg/cm2 for a 1 s duration, 4.5e-7 erg/cm2 for 10 s, and 5e-8 erg/cm2 for 0.1 s. For this computation, we adopt a low threshold at 100 keV and Band model parameters ���0.5, ���2.5 with peak E_0 ~ 600 keV. The optimal orientation is compatible with a large part of the high-probability sky region of the trigger. The limit anywhere in the 90% confidence range of the LIGO Bayestar localisation is at most 50% less stringent.

Investigations of the light curves from the other INTEGRAL instruments covering part of the LIGO localisation region (IBIS VETO, ISGRI, and PICsIT)  did not reveal any significant transient event in the 200 s temporal window centred on LIGO/Virgo G268556, but provide less stringent upper limit on the fluence.

E. Burns (UAH) reports on behalf of the GBM-LIGO Group:
Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton
College), Jordan Camp (NASA/GSFC), Tito Dal Canton (NASA/GSFC), Nelson
Christensen (Carleton College), Valerie Connaughton (USRA), Adam Goldstein
(NASA/MSFC), Rachel Hamburg (UAH), C. Michelle Hui (NASA/MSFC), Pete Jenke
(UAH), Dan Kocevski (NASA/MSFC), Nicolas Leroy (LAL), Tyson Littenberg
(NASA/MSFC), Julie McEnery (NASA/GSFC), Rob Preece (UAH), Judith Racusin
(NASA/GSFC), Peter Shawhan (UMD), Karelle Siellez (GA Tech), Leo Singer
(NASA/GSFC), John Veitch (Birmingham), Peter Veres (UAH), Colleen
Wilson-Hodge (NASA/MSFC)

GBM was observing 82.4% of the initial LIGO BAYESTAR probability map for
G268556 at event time, with a large part of the southern high probability
region occulted by the Earth (specifically, locations within ~67 degrees of
(RA=297.7, Dec=-25.3)). The closest on-board trigger time was more than 12
hours earlier and was due to high particle activity on entry to the SAA.
The untargeted ground-based SGRB search of GBM data between ten and eleven
UTC (Briggs et al., in prep) found no candidates around G268556.

The targeted search of the GBM data ([1], [2]) also did not find a
significant gamma-ray signal. This search processes time scales of 0.265 to
8.192 s within 30 s of the LIGO event. The most significant candidate was
found on the longest timescale with the soft spectral template,
corresponding to a false alarm rate of ~0.003 Hz. The 8.192 s window of
this candidate begins 5.4 s before the T0 of G268556. The location
identified by the search is consistent with the high probability region of
the LIGO annulus, with the GBM localization peaking around (130, 10); the
targeted search location is marginally consistent with a galactic origin.
However, the signal appears in detectors observing different regions of the
sky. Further investigation rules out a solar origin. There is longer term
structure for tens of seconds in the low energy channels of GBM.

Both prompt and longer term upper limits will be sent in a forthcoming
circular.


[1] L. Blackburn et al. 2015, ApjS 217, 8
[2] A. Goldstein et al. arXiv:1612.02395
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The LIGO Scientific Collaboration and Virgo report:

The online pycbc CBC analysis identified a candidate with GraceDB ID
G268556 during processing of data from LIGO Hanford Observatory (H1)
and LIGO Livingston Observatory (L1) at 2017-01-04 10:11:58.599 UTC
(GPS time: 1167559936.599).

G268556 is an event of interest because its false alarm rate, as
determined by preliminary analysis, is less than (i.e., more significant
than) 6.1e-08 Hz (about one in 6 months). The event's properties can be
found at this URL:

https://gracedb.ligo.org/events/G268556

Based on preliminary matched-filter estimates of the masses and spins,
there is a 0% chance that the less massive companion in the binary has
a mass less than 3 Msun. Based on the tidal disruption condition and disk
mass formula of Foucart (PRD 86, 124007), using an implementation
based on Pannarale & Ohme (ApJL 791, 7), we estimate that there is a
0% chance that the system ejected enough neutron-rich material to power
an electromagnetic transient.

One sky map with distance information (e.g., Singer et al. 2016, ApJL 829,
15) is available at this time and can be retrieved from the GraceDB event
page: bayestar.fits.gz, an initial localization generated by the BAYESTAR
pipeline. The probability is concentrated in two long, thin arcs.  The 50%
credible region spans about 400 deg2 and the 90% region about 1600 deg2.
This is the preferred sky map at this time.

This event was also detected by the cWB unmodeled burst search, with a
sky map consistent with the one from BAYESTAR.

The event candidate was not reported by the low-latency analysis pipelines
because re-tuning the calibration of the LIGO Hanford detector is not yet
complete after the holiday shutdown. This resulted in a delay of over 4
hours
before the candidate could be fully examined. We are confident that this is
a
highly significant event candidate, but the calibration issue may be
affecting
the initial sky maps. We will provide an update in approximately 48 hours
which may include an improved sky map.