LIGO/Virgo G274296

The LIGO Scientific Collaboration and Virgo report:

The CWB Burst analysis identified candidate G274296 during real-time
processing of data from LIGO Hanford Observatory (H1) and LIGO
Livingston Observatory (L1) at 2017-02-17 06:05:55.050 UTC (GPS time:
1171346771.050).  This circular has been sent around 13 hours after
the event due to a processing issue.  G274296 is an event of interest
because its false alarm rate, as determined by the online analysis, is
1.7e-07 Hz or about one in 2 months, passing our alert threshold of
~0.5/month. The event's properties can be found at this URL:

https://gracedb.ligo.org/events/G274296

No other GW event candidates were identified within a 300 s window
before or after G274296.

One sky maps are available at this time and can be retrieved from the
GraceDB event page: skyprobcc_cWB.fits, an initial localization
generated by cWB, distributed via GCN notice about 13 hours after the
event.

The morphology of the event candidate is unclear. We can���t confirm
the shape as a chirp, but we can���t discard it.

Updates on our analysis of this event will be sent as they become
available.

P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), A. Rossi (INAF-IASF Bo), A. Melandri, D. Fugazza, S. Covino, (INAF-OAB), E. Palazzi (INAF-IAFS Bo), M. Branchesi (Urbino University/INFN Firenze), L. Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC),  S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPD), V. D'Elia (INAF-ASDC), 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), S. Piranomonte (INAF-OAR), L. Pulone (INAF-OAR), 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 optical/NIR follow-up observations of the LIGO/Virgo GW trigger G274296 (LVC GCN Circ. 20689
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 ) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations were carried out on 2017 Feb 18 from 00:23:52 UT to 03:09:11 UT, simultaneously in the g, r, i, z and H bands. We observed nine nearby (< 20 Mpc) galaxies within the LIGO cWB probability map. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky) starting from the high probability region of the skymap and taking into account the airmass:

RA(J2000)    Dec(J2000)   galaxy_name               Distance (Mpc)
137.0445     5.9276       UGC04797                    17.3
137.5837     7.0379       NGC2775  		      17.3
143.6863     6.4256       PGC027228		      7.78
146.1825     9.6161       IC0559   		      7.68
148.9515     16.4139      UGC05332		      16.1
151.7796     15.9838      UGC05453		      12.43
137.1523     5.2914       PGC2807128		      5.7
143.4337     9.7108       SDSSJ093344.10+094239.0     16.4
144.5559     7.7234       SDSSJ093813.40+074324.2     12.94


A preliminary analysis (also based on visual comparison with the available SDSS fields) reveals no obvious optical/NIR candidate counterpart in the above galaxies down to the following magnitudes: r > 20, H > 17 (AB, 3sigma UL). 
Further analysis is in progress.

V. Savchenko (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group: S. Mereghetti (IASF-Milano, Italy),
C. Ferrigno ((ISDC, University of Geneva, CH), 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, Saclay/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 burst candidate G274296. The satellite was pointing at
RA=17:30:10.94 Dec=-25:04:47.6, close to the low-probability area of 
LIGO localization.
About 2% of the probability was contained in the field of view of 
INTEGRAL IBIS and SPI.
Depending on the location within the LIGO 90% localization region, as 
well as the assumed
counterpart spectrum and duration, the best upper limit is set by the 
anti-coincidence shield
of the spectrometer on board of INTEGRAL (SPI/ACS), the anti-coincidence 
shield of
the IBIS instrument (IBIS/Veto), or by the imaging coded mask 
instruments (IBIS and SPI).
The combination of these instruments covered the full LIGO 90% 
confidence region and
provided stringent constraints on the flux of a possible electromagnetic 
counterpart
in the energy range covered by the INTEGRAL instruments.

We investigated the SPI-ACS, IBIS/Veto, and IBIS/ISGRI light curves between
-500 and +500 s from the trigger time (2017-02-17 06:05:53 UTC) on 
temporal scales
from 0.1 to 100 s, and found no evidence for any deviation from the 
background.
We estimate combined typical 3-sigma upper limits of  3.8e-7 erg/cm2 
(75-2000 keV)
for 8s duration assuming Band model parameters alpha=���1, beta=���2.5, and 
E_ peak = 300 keV.
To derive a limit for a typical short burst with 1 s duration, we use a 
harder cutoff
power law spectrum with a slope of ���0.5 and an Epeak = 500 keV: we find 
a limiting fluence
of 1.4e-7 erg/cm2 (75-2000 keV) at 3 sigma c.l.. These limits assume a 
perpendicular
direction of the burst to the INTEGRAL pointing direction, optimal for 
SPI-ACS sensitivity.
However the extent of the region with optimal response depends on the 
possible source spectrum:
we perform a detailed calculation only for a cutoff powerlaw spectrum 
with a slope of ���0.5 and
an Epeak = 500 keV: we estimate that 35% of the LIGO localization 
probability region is covered
with a range of sensitivity from optimal for SPI-ACS (mentioned above) 
to 50% worse. About 2%
of the LIGO localization in the field of view of IBIS and SPI is covered 
with at least
factor 2 better sensitivity.

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 substantially as a function of the source 
incident angle with an optimal
effective area of about 6000 cm2 at 1 MeV.

J.Y. Wei (NAOC), X.H. Han (NAOC), C. WU (NAOC), N. Leroy (LAL),
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),
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), D. Dornic (CPPM), B.B. Wu (IHEP),
J.L. Atteia (IRAP), D. Götz (CEA), C.Lachaud (APC),
on behalf of the SVOM Gravitational Astronomy group report:

We observed about 1200 square degree (3 sky regions) of the skymap
of the advanced LIGO trigger G274296, with SVOM/Mini-GWAC, at Xinglong
Observatory of NAOC equipped with U9000 camera (FOV~400 square
degree/camera).
SVOM/Mini-GWAC 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 52% prior
probability that these 3 regions contain the true location of the
source.

The coordinates of the 3 regions and observation time are list following:

start-obs(UTC) end-obs(UTC) Ra Dec Camera_ID
2017-02-17 12:20:29.0 2017-02-17 13:45:04.7 10:34:48.326 +29:29:08.60 C1
2017-02-17 13:45:30.2 2017-02-17 17:12:33.6 11:58:53.431 +29:29:28.69 C1
2017-02-18 10:53:52.3 2017-02-18 12:57:00.8 09:12:10.933 +10:39:50.19 C6

The first image was taken ~6 hours 20 minutes after the event trigger.
Note that the observations on Feb. 18th. have been done under poor
weather conditions. The limit magnitude is ~10 mag in R band.
No any significant transient is found in our online pipeline. The
image analysis is ongoing in detailed processing with our offline
pipeline.

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina


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 J042250.16-820415.4 discovery - PSN in low surface brightness 
galaxy



MASTER-OAFA (Argentina, San Huan Uni) auto-detection system discovered OT 
source at (RA, Dec) =  04h 22m 50.16s -82d 04m 15.4s on 2017-02-19.12023 
UT during LIGO/VIRGO alert inspection  (Peter Shawhan, GCN 20689
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 ) .

The OT unfiltered magnitude is 15.9m (limit 20.0m).

The OT is seen in 2 images. There is no minor planet at this place.

We have reference image without OT on 2016-09-25 03:50:02 UT with 
unfiltered  magnitude limit 20.0m.

There is Galalaxy   ESO 15-10 with offset:P  d_ra 0.1E   ddec 1.6N.

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/042250.16-820415.4_S0swHrk.png
http://observ.pereplet.ru/images/PSN042250.1-820415.4.jpg

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

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

MASTER-Tunka (Sibiriya, Baykal, -30C)detected two additional OTs during 
LIGO/VIRGO alert inspection  (Peter Shawhan, GCN 20689
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 ; Lipunov et al., 
GCN 20696
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 ).

MASTER OT J111410.86+383448.2  - AGN.


MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 11h 
14m 10.86s +38d 34m 48.2s on 2017-02-18.77808 UT.
The OT unfiltered magnitude is 18.6m (limit 19.6m).

The OT is seen in 2 images. There is no minor planet at this place.

We have reference image without OT on 2011-04-23.66288 UT with unfiltered 
magnitude limit 20.2m.
There is  object SDSS DR10 catalogue of candidate quasars 
(Brescia+, 2015, 2015MNRAS.450.3893B )
Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/111410.86383448.2.png


MASTER OT J104314.39+241518.4 -  PSN in the SDSS galaxy with ~4 arcsec 
offset.


MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 10h 
43m 14.39s +24d 15m 18.4s on 2017-02-18.73677 UT.
The OT unfiltered magnitude is 18.8m (limit 19.3m).

The OT is seen in 1 image. There is no minor planet at this place.

We have reference image without OT on 2011-03-30.69752 UT with unfiltered 
magnitude limit 20.4m.

THERE is SDSS galaxy J104314.36+241522.4 in 4 arcsec from OT.

Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/104314.39241518.4.png

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, J.Maund (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 G274296 (GCN #20689
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 ). Targeted observations containing ~82% of the source location probability were performed between 20:40 UT Feb 17 2017 and 06:55 UT Feb 18 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 17 and 51 times during that observing window. These regions were also observed immeditately preceding the GW trigger as part of a survey mode program the night before with 2x30s exposures at each position between 1:21 and 6:54 UT Feb 17 2017 as well as on Feb 18 2017 between 1:14 and 6:14 UT.

Conditions were clear and stable. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing.

K. C. Chambers (IfA), K. W. Smith (QUB), M. E. Huber (IfA),
D. R. Young, S. J. Smartt, (QUB), M. Coughlin (Harvard), T.-W. Chen
(MPE), L. Denneau, H. Flewelling, A. Heinze, E. Kankare (QUB),
T. Lowe, 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, M. Willman (IfA), D. E. Wright (QUB)

We report that we covered 501 square degrees on the first night
following the release of the G274296 alert. We began taking data at
2017-02-18.29 UT (57802.29; 25hrs after the event detection).  We
estimate that this first night of data coverage corresponds to a
probability of containing the source of 44.7%, (based on the cWB map
skyprobcc_cWB.fits ; GCN 20689
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 ). Maps will be posted on GraceDB.

Images were taken in the Pan-STARRS i-band filter in a series of
overlapping 45s exposures, with typically 4-8 images at each position.
Difference images were produced by subtracting the Pan-STARRS1 3Pi
reference image from these separate 45s exposures (Chambers et
al. arXiv:1612.05560
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 , and available at http://panstarrs.stsci.edu).
We reach i ~ 21 - 21.5 in the individual exposures. 

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 difference images.  

In the following table, we give our 70 targets, sorted by magnitude.
To select these targets we required a minimum of 2 detections in these
sets of images. There are 10 transients in galaxies with redshifts
(from SDSS DR12), and these are listed first. The rest of the
transients are not obviously associated with a galaxy with a redshift.
The closest transient is PS17bfl (i=21.06) 2.9" offset from 2MASX
J11504136+3715422 : z=0.035, mu=35.8, D=140 Mpc, M_i = -14.8.  With
this relatively faint  absolute magnitude, spectroscopic classification of
this transient in particular is recommended.

Variable sources which are likely AGN/QSOs or variable stars have, as
far as possible, been removed from this transient list.  We remove
likely AGN/QSOs either from catalogues, SDSS DR12 spectra, or nuclear
transients which are in galaxies with previous core variability seen
in Pan-STARRS general survey mode. Similarly variable stars or stellar
outbursts are removed through catalogue matching. The following list
is composed of SN-like transients, as far as we can tell from current
data.

We found 10 transients which are previously known transients or 
supernovae found in preceding weeks or months before G274296, and 
we list them here for reference. 

Name    RA          DEC         MJD-Disc                mag(i)      z
Transients with host spectroscopic redshifts :
PS17bda 09:30:36.08 +11:29:53.6 57802.32131  19.41   0.090
PS17bel 10:50:34.63 +30:25:30.7 57802.30825  20.09   0.116
PS17bew 11:13:30.66 +29:40:02.9 57802.38998  20.14   0.046
PS17bdt 10:17:28.88 +22:24:57.4 57802.30240  20.26   0.048
PS17bfg 11:45:39.79 +33:23:38.9 57802.41584  20.67   0.141
PS17bdr 10:11:35.41 +19:15:46.7 57802.30099  20.74   0.078
PS17bfy 12:06:57.57 +35:25:36.9 57802.40619  21.01   0.081
PS17bfl 11:50:41.38 +37:15:45.0 57802.40490  21.06   0.035
PS17bdz 10:27:42.90 +28:21:20.3 57802.30500  21.06   0.161
PS17bef 10:38:13.94 +25:49:24.6 57802.30435  21.19   0.078

Transients with no host spectroscopic redshifts :
PS17bgn 11:31:52.98 +29:59:45.1 57802.41391  18.33   bright nuclear transient 
PS17bfc 11:29:33.54 +34:12:07.1 57802.39565  19.42   
PS17beo 10:53:24.67 +28:51:27.1 57802.30825  19.51   
PS17bgt 11:58:09.80 +34:04:38.0 57802.40426  19.81   
PS17bek 10:47:41.90 +26:50:06.0 57802.30629  19.85   
PS17bcv 09:16:27.70 +03:35:25.1 57802.28975  19.90   
PS17bgf 10:59:22.27 +29:44:11.3 57802.41064  19.91   
PS17bed 10:31:52.14 +24:26:31.0 57802.35657  20.10   
PS17bep 10:57:33.56 +31:05:16.0 57802.42273  20.17   
PS17bdv 10:21:15.87 +23:38:53.3 57802.30370  20.23   
PS17bem 10:51:31.88 +26:29:10.4 57802.30760  20.29   
PS17bgm 11:28:24.06 +30:06:26.5 57802.39965  20.31   
PS17bgx 09:20:37.00 +12:53:17.8 57802.48646  20.37   
PS17bgz 10:29:39.67 +26:38:57.9 57802.43359  20.45   
PS17bdm 10:05:41.12 +22:31:24.9 57802.35248  20.47   
PS17bev 11:11:17.74 +31:28:53.4 57802.39824  20.57   
PS17bfh 11:46:47.23 +31:34:13.4 57802.40169  20.63   
PS17bcs 09:02:44.47 +02:12:41.1 57802.44885  20.65   
PS17bdn 10:05:43.77 +22:31:05.8 57802.29958  20.66   
PS17bff 11:42:16.34 +32:36:01.9 57802.40169  20.70   
PS17bgu 12:04:37.88 +32:07:42.4 57802.31211  20.74   
PS17bgp 11:42:27.80 +31:02:12.5 57802.40169  20.74   
PS17bfm 11:55:15.38 +35:50:48.6 57802.40490  20.80   
PS17beg 10:40:17.22 +27:47:37.2 57802.30629  20.82   
PS17bgr 11:47:04.86 +35:13:14.0 57802.40490  20.85   
PS17bgd 10:28:30.41 +22:30:23.2 57802.30370  20.90   
PS17beh 10:42:02.04 +29:51:18.1 57802.30564  20.97   
PS17bgs 11:55:32.52 +29:55:29.7 57802.40362  20.99   
PS17bgo 11:33:14.22 +30:53:06.1 57802.39965  21.02   
PS17bdx 10:22:58.46 +24:38:17.0 57802.35590  21.02   
PS17bgc 10:22:36.15 +21:12:37.9 57802.30163  21.03   
PS17bgw 12:09:21.73 +36:46:08.2 57802.40619  21.05   
PS17beb 10:31:19.80 +26:56:54.5 57802.33322  21.05   
PS17bcx 09:24:03.25 +08:04:33.8 57802.34338  21.05   
PS17bgi 11:12:46.03 +28:38:50.4 57802.41131  21.10   
PS17bfz 09:16:10.00 +08:37:10.4 57802.45144  21.12   
PS17bdu 10:20:34.54 +20:12:51.4 57802.30163  21.13   
PS17bgb 09:46:52.25 +10:39:51.1 57802.29491  21.13   
PS17bei 10:42:41.75 +25:35:06.8 57802.35990  21.15   
PS17bdw 10:22:57.59 +24:38:22.1 57802.38244  21.15   
PS17bdb 09:32:00.94 +15:00:40.2 57802.29362  21.16   
PS17bcu 09:15:24.05 +03:45:37.4 57802.34263  21.16   
PS17bee 10:34:00.57 +26:56:00.3 57802.35723  21.17   
PS17bfk 11:50:33.88 +35:33:45.1 57802.40490  21.19   
PS17bge 10:57:22.95 +30:22:03.4 57802.38805  21.19   
PS17bfo 11:57:44.78 +32:54:59.9 57802.39192  21.20   
PS17bgq 11:43:47.66 +32:44:07.0 57802.40169  21.21   
PS17bgg 11:03:12.23 +31:56:23.9 57802.33709  21.21   
PS17bgl 11:24:07.20 +36:13:14.2 57802.40233  21.36   
PS17bds 10:16:57.14 +24:34:18.8 57802.30240  21.40   
PS17bfb 11:24:05.27 +33:26:57.0 57802.40105  21.42   
PS17bgh 11:12:08.04 +30:21:11.1 57802.38998  21.45   
PS17bet 11:08:34.19 +30:03:46.3 57802.38934  21.46   
PS17bgy 09:32:17.63 +13:36:14.5 57802.48711  21.50   
PS17bgv 12:08:20.09 +38:45:20.8 57802.40554  21.53   
PS17bdl 10:04:29.91 +22:01:20.9 57802.32850  21.54   
PS17bgk 11:15:17.75 +30:53:09.5 57802.42537  21.57   
PS17bgj 11:15:16.28 +32:14:05.4 57802.39062  21.64   
PS17bga 09:16:19.41 +00:47:06.0 57802.44950  21.69   
PS17bfe 11:41:34.79 +30:39:15.2 57802.40169  21.73   


Already known objects : 
PS17bhc 09:47:26.75 +19:36:31.1 57789.49854  21.00   
PS17bhb 09:44:33.28 +15:15:42.4 57789.50327  21.61   
PS17bha 09:27:42.08 +12:00:14.1 57789.47490  20.78   
PS17beu 11:10:52.80 +28:16:27.8 57802.30954  19.18   AT2017nf
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PS17bfw 12:01:07.05 +38:52:35.0 57802.40554  20.66   CSS160514-120107+385236
PS17abg 10:50:24.61 +23:59:21.5 57802.35990  21.24   AT2017qh
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PS17bdp 10:06:29.10 +22:26:43.9 57802.32850  16.89   SN2016idl
PS17gn 10:01:11.46 +19:29:43.2 57802.29814  20.91   AT2016ieg
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PS17bdj 10:00:18.25 +19:23:05.1 57802.29814  19.85   MLS160217-100018+192305
PS17m 09:34:55.90 +06:17:27.0 57802.29169  20.01   AT2017D

B. Li (PMO/CAS), D. Xu (NAO/CAS), H.B. Zhao, G.T. Zhaori, H. Lu, R.Q.
Hong, L.F. Hu (PMO/CAS), T.M. Zhang, X. Zhou, H.X. Feng, Z.P. Zhu
(NAO/CAS), J.Z. Liu, H.B. Niu, Y. Zhang, X. Zhang, G.X. Pu, S.G. Ma,T.Z.
Yang, F.F. Song (XAO/CAS), J. Mao, J.M. Bai (YNAO/CAS)  report on behalf
of the Gravitational Wave Follow-Up Network by NAO-PMO-XAO-YNAO in China
(GWFUNC):

We have performed tiled observations of LIGO/Virgo G274296 (LVC, GCN
20689
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 ) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST)
at Xuyi, Jiangsu, and the 0.6/0.9-m Schmidt telescope at Xinglong,
Hebei, China.

CNEOST has a FOV of 3.0x3.0 deg^2, and covered ~1400 square degrees from
10:40:00.05 UT to 22:01:49.81 UT on 2017-02-18 in the Sloan r-filter.
The skymap coverage is at

https://dl.dropboxusercontent.com/u/3665676/G274296/skymap20170218NEOST.pdf

and the typical limiting magnitude is m(r)~20.0.

Preliminary analysis from our vetting procedure reveals several
supernova (SN) candidates and quite a few AGN candidates.

Most SN candidates were already reported by different surveys days
before the G274296 trigger time (i.e., 06:05:55.05 UT on 2017-02-17). We
here note one SN candidate discovered after the GW trigger time, dubbed
as PTSS-17gpm and observed at 19:01:33 UT, at coordinates:

R.A. (J2000) = 11:59:59.45
Dec. (J2000) = +31:57:46.98

with m(r)~18.6. It was also discovered by the ATLAS project, dubbed as
AT 2017axh
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  or ATLAS17bbz and discovered by on 12:48:57 on 2017-02-17.
This source is positionally coincident with the galaxy SDSS
J115959.38+315745.7, which has m(r)=19.47 and a PhotoZ=0.09+/-0.04.

Further observations are planned.

M. Im, S. Lee, C. Choi, G. Lim, S. Hwang, H. M. Lee (SNU), S. Pak, T.-G. Ji
(KHU), H.-I. Sung (KASI), S. Ehgamberdiev (UBAI) on behalf of the
KU collaboration

We observed a 49 square degree of the probability area of G274296 using a
wide-field 0.25m telescope (a piggyback system on the 0.8m telescope) at
the McDonald observatory, Texas, USA. The observation was performed in
R-band, starting at 2017-02-18 11:27 (UT). A preliminary analysis of the
data shows the detection limit of  R ~ 17.8 mag at 5-sigma for a point
source detection. The covered fields are indicated below, each having a
2.35 deg x 2.35 deg field of view centered at the coordinates. The central
parts of the fields are covered by the 0.8m telescope simultaneously,
covering 46.2 arcmin x 46.2 arcmin field of view to the depths about 0.7
magnitude deeper than the 0.25m data. The analysis of the data is ongoing.

Field    RA                Dec
G1:  12:10:00.00   40:30:00.0
G2:  12:10:00.00   38:00:00.0
G3:  12:10:00.00   35:30:00.0
G4:  12:20:00.00   40:30:00.0
G5:  12:20:00.00   38:00:00.0
G6:  12:20:00.00   35:30:00.0
G7:  12:30:00.00   40:30:00.0
G8:  12:30:00.00   38:00:00.0
G9:  12:30:00.00   35:30:00.0

���

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 G274296 event using the initial LIGO skyprobcc_cWB probability map at event time (LVC GCN Circ. 20689
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 ). 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/G274296.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 34% 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 G274296 event time. The expected number of atmospheric background events in the 90% contour region visible by ANTARES is ~5.4e-3 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going neutrino coincidence.

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

Sujay Mate (IUCAA), Varun Bhalerao (IIT Bombay), 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:

We carried out offline analysis of data from AstroSat CZTI in a 100 second window centred on the G274296 trigger time, UT 2017-02-17 06:05:55.050, to look for any coincident hard X-ray flash. CZTI is a coded aperture mask instrument that has considerable effective area for about 29% of the entire sky. Based on the pointing direction of AstroSat at the time of the GW event and the LIB skymap provided by LVC (skyprobcc_cWB.fits,0), the sky visible to CZTI has 6.3% probability of containing the EM counterpart.

CZTI data were de-trended to remove orbit-wise background variation. We then searched data from the four independent, identical quadrants to look for coincident spikes in the count rates. Searches were undertaken by binning the data in 0.1s, 1s and 10s respectively. Statistical fluctuations in count rates were estimated by using data from 10 neighbouring orbits. We selected confidence levels such that the probability of a false trigger in this 100s window is 10^-4. We do not find any evidence for any hard X-ray transient in this window. We model the source with a band function using standard band function parameters, with alpha = -1, beta = -2.5 ans E_peak = 300 keV. The sensitivity of CZTI varies with direction. We weight the sensitivity by the CWB probability density map to calculate upper limits on any coincident emission from the source. In the 30-200 keV, the upper limits for source fluence are 1.8e-07 ergs/cm^2, 4.4e-07 ergs/cm^2 and 1.1e-06 ergs/cm^2 for search timescales of 0.1, 1, and 10 seconds respectively. The corresponding flux upper limits for the three timescales are 1.8e-06, 4.4e-07, and 1.1e-07 ergs/cm^2/sec respectively.  

Plots showing CZTI sensitivity as a function of direction can be found at https://gracedb.ligo.org/apiweb/events/G274296/files/G274296_CZTI_limits.pdf,0

About 30% of the localisation region had emerged from earth occultation 2200 seconds after the trigger. Searching the data from T+2200s to T+3200s for transients with 10s duration, we do not find any significant transient candidate above background noise.

Nicola Omodei (Stanford), Giacomo Vianello (Stanford),  Daniel Kocevski 
(NASA/MSFC) and Sara Buson (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 G274296.
The region of the LIGO map with probability >90% entered the LAT field 
of view at T0+400 (T0 = 2017-02-17 06:05:53 UTC), and reached full 
coverage at about 7ks from T0.
We searched for a transient counterpart within the LIGO 90% probability 
contour in the time window from T0  to T0 + 10 ks and found no 
significant new sources.
We also performed a search that adapted the time interval of the 
analysis to the exposure of each region of the sky. No significant 
candidate counterpart was found.

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.

F. Taddia, C. Barbarino, A. Nyholm, C. Fremling, J. Sollerman (OKC),
M. T. Botticella (INAF-Capodimonte), M. Fraser (UCD), C. Inserra,
E. Kankare, K. Maguire, S. J. Smartt, K. W. Smith, D. Wright, D. Young
(QUB), M. Sullivan (Southampton), S. Valenti (UC Davis), O. Yaron,
I. Manulis (Weizmann), E. Cappellaro (INAF-Padova), K. C. Chambers
(IfA), M. E. Huber (IfA), M. Coughlin (Harvard), T.-W. Chen (MPE),
L. Denneau, H. Flewelling, A. Heinze, T. Lowe, E. A. Magnier (IfA),
A. Rest (STScI), B. Stalder, A. S. B. Schultz (IfA), C. W. Stubbs
(Harvard) J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland, M. Willman
(IfA)


PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see
Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org), reports the
following supernova classifications related to G274296 within the cWB
map skyprobcc_cWB.fits (GCN 20689
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 ).

Targets were supplied by Pan-STARRS as in Chambers et al.
(GCN20699
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 ). For Pan-STARRS information, see Chambers et al. 2016
(arXiv:1612.05560
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 , and http://pswww.ifa.hawaii.edu).  We selected
targets brighter than i=20.5 and accessible from La Silla.

All observations were performed on the ESO New Technology Telescope at
La Silla on 2017 February 19, using EFOSC2 and Grism 13 (3985-9315A,
18A resolution).  Classifications were done with SNID (Blondin &
Tonry, 2007, ApJ, 666, 1024) and GELATO (Harutyunyan et al., 2008,
A&A, 488, 383). Classification spectra and additional details can be
obtained from http://www.pessto.org (via WISeREP).

Name        RA (J2000)  Dec (J2000)  Disc. Date  Disc Mag   z      Type      Phase        Notes
PS17bcv     09 16 27.70 +03 35 25.2   20170218     19.9    0.104   IIn        ?                  (1)
PS17bda     09 30 36.08 +11 29 53.6   20170218     19.4    0.090   Ia         -3 to +3 d    (2) 
PS17bgx     09 20 37.01 +12 53 17.8   20170218     20.4    ?          ?          ?                  (3)
PS17bdt      10 17 28.88 +22 24 57.5   20170218     20.3    0.048   II         +12 d            (4)
PS17bdv     10 21 15.88 +23 38 53.2   20120218     20.4    0.14     Ia         +8 to +10 d  (5)
PS17bel      10 50 34.64 +30 25 30.7   20120218     20.0    0.116   Ia           +4 to +7 d   (6)
PS17beo     10 53 24.68 +28 51 27.1   20120218     19.6    0.217   IIn          +30 d          (7)
PS17bgn     11 31 52.98 +29 59 45.1   20120218     18.3    0.148   SLSN II   >+50d        (8)
PS17bek     10 47 41.90 +26 50 06.0   20120218     19.7    0          Stellar        -              (9)

Notes 

(1) Narrow Halpha and Hbeta in emission. Offset from the host-galaxy
center.

(2) Best SNID matches to several 1991T-like SNe Ia before and around
maximum. Redshift from SDSS.

(3)  Blue featureless spectrum. 

(4) Best SNID fit to SN 2004et at +12 d. Other good fits with SNe II
at +0 d and +20 d. Redshift from SDSS.

(5) Best SNID match with normal SN Ia 2002dj at +9 d. Several other
good matches with normal SNe Ia at similar age.

(6) Best SNID match with several normal SNe Ia at +4 to +7 d. Redshift
from SDSS.

(7) Good GELATO match to SN IIn 2010jl at +28 d. Absolute magnitude
-20.2 mag.

(8) Redshift and phase based on the best SNID match to SN IIL
1979C. Broad double-peaked Halpha and Hbeta, similar to 
nebular type II spectra.  Absolute magnitude -20.8 mag, very 
bright for inferred phase. 

(9) Narrow Halpha detection at z=0. Blue spectrum with black body
temperature of about 10000 K.

I. Bartos, S. Countryman (Columbia), C. Finley (U Stockholm), E. Blaufuss (U Maryland), R. Corley, Z. Marka, S. Marka (Columbia) on behalf of the IceCube Collaboration

We searched IceCube online track-like neutrino candidates (GFU) detected in a [-500,500] second interval about the LIGO-Virgo trigger G274296.  We compared the candidate source directions of 3 temporally-coincident neutrinos to the cWB skymap, with the following parameters:

#  dt[s] RA[deg] Dec[deg] E[TeV]  Sigma[deg]
--------------------------------------------
1. -279  136.6   20.8      9.55   1.7
2. -134  299.3   14.3     10.53   0.6
3.  228    9.8    7.7      5.36   0.4

The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES detected by IceCube within the 500 second window surrounding G274296 within the cWB skymap.

In addition, we performed coincident searches with other IceCube data streams, including the high-energy starting events (HESE) and Supernova triggers.  HESE events have typical energies > 60 TeV and start inside the detector volume, leading to a relatively pure event sample with a high fraction of astrophysical neutrinos.  The SN trigger system is sensitive to sudden increases in photomultiplier counts across the detector, which could indicate a burst of MeV neutrinos.   NO COINCIDENT HESE OR SUPERNOVA SIGNATURES were identified by these searches.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica.  For a description of the IceCube realtime alert system, please refer to<http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1610.01814
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 >; for more information on joint neutrino and gravitational wave searches, please refer to<http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1602.05411
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 >.

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

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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-SAAO reobserved PSN  MASTER OT J042250.16-820415.4, discovered on 
2017-02-19.12023UT (Lipunov et al., GCN 20696
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 )  in W,BVRI .

This PSN arises, so it has possibility to explode on the 17th of Feb 2017 
(Peter Shawhan, GCN 20689
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 ) .

Preliminary photometry is the following:
     Date       UT            mag
2017-02-19 02:37:46 UT      W=16.3 (discovery date)
2017-02-19 19:25:59 UT      W=16.2
2017-02-20 19:23:54 UT      W=15.7
2017-02-20 18:43:57 UT      V=16.0
2017-02-20 19:07:59 UT      I=15.9
2017-02-20 19:07:59 UT      R=16.0

The spectroscopy observations are required  its age and type 
determination.

Light curve is available at 
http://master.sai.msu.ru/static/OT/MASTEROTJ04225016-8204154.jpg

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

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

MASTER continues inspection of LIGO event G274296 (Shawhan et al. 
GCN20689
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 , Lipunov et al. GCN20696
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 ). The cover map of MASTER inspection 
survey, the position of MASTER OTs inside LIGO error-box is presented at 
http://master.sai.msu.ru/static/MASTERGW170217full.jpg

MASTER OT J105519.53+365834.1 - bright PSN in 1.2"E,1.2"S from the center 
of  PGC032819  (Sc type   http://leda.univ-lyon1.fr/ledacat.cgi?PGC032819 )

  MASTER-Tunka (Near Baykal, Irkutsk, Russia) auto-detection system 
discovered optical transient at 
RA(2000)=10h 55m 19.53s +36d 58m 34.1s  on
2017-02-18 18:18:18UT with unfiltered m_OT=15.7 (MASTER W=0.2B+0.8R 
calibrated by USNO-B1 thousands stars in the field).
This PSN is seen on 3 images and is located in 1.2"E,1.2"S from the center 
of spiral  PGC032819 .

We have reference images without OT on 2016-01-01 21:12:22 with mlim=19.9, 
on 2016-12-25 21:56:41UT with mlim=18.8.

Spectral observatios are required.

The discovery and reference images are 
http://master.sai.msu.ru/static/OT/MASTEROTJ105519.53+365834.1.jpg

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

Lipunov et al. (GCN 20712
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 ) reported the discovery of a very bright,
mag=15.7 transient in the sky localisation map of G274296 (GCN20689
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 )
at the position : 

MASTER OT J105519.53+365834.1 RA(2000)=10h 55m 19.53s +36d 58m 34.1s  

at 2017-02-18 18:18:18 UT (MJD=57802.76271) 

and close to (within 1.7���) of the centre of an edge-on spiral galaxy
at z = 0.043224 (KUG 1052+372; PGC 032819)

With the ATLAS telescope system (see Tonry et al. GCN 20382
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  and
www.fallingstar.com), we confirm the reality of this bright transient,
however it exploded well before the GW detection G274296.  The MJD of the
GW source was 57801.2541094 as announced in GCN20689
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 .

In ATLAS routine survey mode we detect the transient (internally called
ATLAS17bbp) on two images on the night of MJD=57794 at mag = 18.23
(orange filter) and again on 5 images on each of 57798 and 57802, the
latest with m=17.40 +/- 0.07 (the orange bandpass is approximately
equivalent to o ~ 0.56r+0.44i).

The difference in the magnitudes between ATLAS and MASTER is likely
due to ATLAS performing difference imaging photometry and the transient being
located close to the galaxy core.

The ATLAS17bbp coordinates are RA=163.83115 DEC=+36.97640
(10:55:19.47 +36:58:35.0)

While this is certainly real, and within the LIGO localisation banana,
it has an explosion date at least 7 days before G274296.  We measure a
1.2" difference in the astrometric coordinates of PGC 032819 and
ATLAS17bbp, but further analysis is required to determine if it
actually is coincident with the galaxy nucleus.

The source fell outside the northern egde of the Pan-STARRS1 coverage
(Chambers et al. GCN 20699
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 ).

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

We carried out optical follow-up observations of the LIGO/Virgo GW trigger G274296 (LVC GCN Circ. 20689
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 ) with the Copernico 1.82m telescope (INAF OAPd, Asiago-Ekar, Italy). The observations were carried out starting on 2017 Feb 17 from 20:56:11.7 UT, until 2017 Feb 18, 03:22:58.5 UT, using Sloan g-band. We observed several nearby (< 20 Mpc) galaxies within the LIGO cWB probability map. The pointing sequence was generated using the GWsky script (https://github.com/ggreco77/GWsky <https://github.com/ggreco77/GWsky>) starting from the high probability region (30%) of the skymap (with the exception of the first three follow-up observations in the field of NGC4096, after GCN 20688
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 ) and taking into account the airmass:

p01   12:06:00.60     +47:28:39        NGC4096 (follow-up after GCN 20688
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 )
p02   12:06:00.59     +47:28:45        NGC4096 (follow-up after GCN 20688
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 )
p03   12:06:00.55     +47:39:59        Norther of NGC4096 (GCN 20688
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 )
p04   10:51:20.65     +32:46:00        NGC3413
p05   10:56:19.93     +31:16:10        2MASX J10562004+3116126
p06   10:12:53.15     +22:43:15        MCG+04-24-018
p07   10:32:17.28     +27:40:10        NGC3274
p08   11:52:55.65     +36:59:16        NGC3941
p09   11:51:45.69     +38:00:55        NGC3930
p10   10:11:08.79     +23:52:31        LEDA 1695322
p11   10:17:39.63     +22:48:33        2MASX J10173965+2248358
p12   10:11:16.68     +24:03:56        AGC 721972
p13   09:21:00.10     +11:03:39        LEDA 26453
p14   09:21:00.12     +11:03:39        LEDA 26453
p15   09:21:01.14     +11:03:39        LEDA 26453
p16   09:55:48.15     +16:24:48        UGC5332
p17   10:31:48.30     +25:18:26        SDSS J103149.00+251816.0
p18   11:58:29.99     +38:04:34        UGC6955
p19   10:10:33.29     +22:00:36        LEDA 139255
p20   10:27:13.83     +24:09:44        LEDA 1701087
p21   10:23:44.64     +27:06:44        LEDA 1798058
p22   10:31:56.20     +28:01:37        LEDA 1824266
p23   12:03:53.89     +38:54:11        LEDA 2139249
p24   09:14:58.10     +06:00:17        SDSS J091457.31+060016.7
p25   10:27:16.93     +28:30:42        SDSS J102716.85+283039.6
p26   10:24:14.30     +24:25:46        AGC 731449
p27   10:32:18.79     +27:39:57        SDSS J103217.21+274007.7
p28   10:35:11.18     +25:27:00        SDSS J103511.05+252704.0
p29   10:28:58.61     +25:17:07        AGC 731454
p30   10:20:00.21     +24:25:55        SDSS J102002.81+242615.0
p31   10:19:59.99     +24:47:32        SDSS J101959.88+244724.6
p32   09:58:17.18     +21:05:19        SDSS J095816.17+210520.4
p33   09:33:44.60     +09:42:35        SDSS J093344.10+094239.0
p34   09:21:15.41     +09:42:55        SDSS J092114.97+094352.2
p35   09:29:51.95     +11:55:41        SDSS J092951.83+115535.7

The upper limit of the measured g-band magnitudes is 20.5-21.0 (AB mag, 3sigma).
Based on comparison with SDSS field templates we detected a SN candidate at 
RA=10:27:28.025, Dec=+24:12:45.85 with magnitude g = 19.31 +/- 0.05 mag (AB). 
The object is hosted in a faint field galaxy SDSS J102727.87+241249.9, with photometric redshift photoZ=0.074 (SDSS DR13).
Assuming the above redshift, the absolute magnitude is around -18.3. 
Few other transients are likely faint variable stars, since they are already visible in the SDSS images.

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

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San 
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

During inspection of LIGO event G274296 (Shawhan et al.
GCN20689
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 , Lipunov et al. GCN20696
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 , GCN20712
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 ) MASTER-Tunka  detected the 
following additional optical transients:

1) MASTER OT J144935.82+343749.9 discovery - PSN (18.0m) in SDSS 
galaxy(r=20.9)

During GW inspection survey MASTER-Tunka auto-detection system discovered 
OT source at (RA, Dec) = 14h 49m 35.82s +34d 37m 49.9s on 2017-02-21.77409UT.

The OT unfiltered magnitude is 18.0m (mlimit 19.4m).

The OT is seen in 2 images. There is no minor planet at this place.

There is SDSS galaxy with red m=20.94 http://skyserver.sdss.org/dr9/en/tools/quicklook/quickobj.asp?id=1237662226228118204

We have reference image without OT on 2016-12-05.94591 UT with unfiltered 
magnitude limit m=20.0m.

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/144935.82343749.9.png



MASTER OT J082950.02+274024.3 - possibly QSO outburst

During GW inspection survey MASTER-Tunka auto-detection system discovered 
OT source at (RA, Dec) = 08h 29m 50.02s +27d 40m 24.3s on 2017-02-21.56417 UT.
The OT unfiltered magnitude is 19.1m (limit 20.1m).

The OT is seen in 3 images. There is no minor planet at this place.

We have reference image without OT on 2015-11-19.71169 UT with unfiltered 
magnitude limit m=20.1m.

There is GALEX source in 0.8" and this OT is in 1" from	SDSS DR10 
catalogue of candidate quasars (Brescia+, 2015), i.e. our OT is QSO in 
outburst.

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/082950.02274024.3.png

T. Nakaoka, T. Abe, M. Chogi, M. Yoshida, Y. Utsumi and K. S.
Kaawbata (Hiroshima University) on behalfof J-GEM collaboration,

We performed optical spectroscopy of the optical transient MASTER
OT J105519.53+365834.1PSN in PGC 032819 (Lipunov et al. GCN 20712
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 )
with 1.5-m Kanata telescope at Higashi-Hiroshima Observatory on
2017 Feb 21. The spectrum shows a broad absorption line around
620 nm. The overall features suggest that this PSN is a SN 1991T
like bright Type Ia supernova around maximum brightness. A
comparison with a library of supernova spectra using GELATO
(Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that the
spectrum gives a good match to SN 1998es at -3.5 days before
B-band maximum.

R. Ferretti (OKC), R. Lunnan (Caltech), M. M. Kasliwal (Caltech), L. P.
Singer (NASA/GSFC), S. B. Cenko (NASA/GSFC), D. Cook (Caltech), C. Cannella
(Caltech),  A. van Sistine (UWM), T. Barlow (Caltech), V. Bhalerao (IUCAA),
J. Rana (IUCAA), A. A. Miller (Northwestern/Adler), Y. Cao (UW)

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

We performed tiled observations of LIGO/Virgo G274296 (LVC, GCN 20689
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 )
using the Palomar 48-inch Oschin telescope (P48) on the night of 2017-02-21
UTC. We imaged 111 fields spanning 807 square degrees, with a 54% chance of
containing the true location of the source. Of these, 69 fields (502 square
degrees; 42% probability) were imaged twice and searched for transient
candidates.

During preliminary sifting through candidate variable sources using image
subtraction by our IPAC pipeline (Masci et al. 2016), and applying standard
iPTF vetting procedures, we flagged the following optical transient
candidates (60 total) for further follow-up:

name           RA            Dec          time             mag
z         notes
--------      ----------     ----------   -----           -----
------     ---------
iPTF17bed    234.991732     +34.088243    2457806.0160    20.17
0.138       photz; at edge of galaxy
iPTF17bec    232.665446     +33.928645    2457806.0160    19.90
0.0482      specz; irregular galaxy; fading (0.34 mag intra-night)
iPTF17beb    235.828735     +32.682827    2457806.01757   19.03
0.07        photz
iPTF17bdz    174.715936     +33.828372    2457805.90013   20.05
0.0327      specz;  nuclear edge-on
iPTF17bdy    178.129375     +35.456339    2457805.90162   20.30
0.0943      specz;  slightly off-center
iPTF17bdw    178.329915     +36.442293    2457805.90313   20.29
0.18        photz
iPTF17bds    183.323594     +39.266026    2457805.9061    20.11
0.13        photz; fading (0.40 mag intra-night)
iPTF17bdq    181.290430     +37.270222    2457805.90762   19.94
0.0226      specz
iPTF17bdp    182.529730     +36.393440    2457805.90762   20.08
0.2432      specz; nuclear (SDSS QSO)
iPTF17bdn    184.075520     +40.796273    2457805.93462   20.57
0.136       photz
iPTF17bdl    183.608407     +42.063649    2457805.9346    19.65
0.0231      specz; nuclear?
iPTF17bdk    186.611638     +40.726698    2457805.9346    20.55
0.0699      specz; nuclear?
iPTF17bdj    185.368397     +42.208415    2457805.93462   19.51
0.1206      specz
iPTF17bdf    188.315478     +36.824458    2457805.93763   19.68
0.095       photz
iPTF17bde    187.281321     +36.457123    2457805.93763   19.58
0.0714      specz; slightly off-center
iPTF17bdd    191.013043     +41.168996    2457805.93912   19.04
0.0237      specz; nuclear?; rising (0.48 mag intra-night)
iPTF17bdc    192.553197     +36.464676    2457805.9421    20.49
0.1448      specz; at edge of galaxy
iPTF17bda    193.915287     +39.855467    2457805.9436    19.21
0.38        photz
iPTF17bcz    196.354965     +39.004452    2457805.9436    19.59
0.0808      specz; off-center
iPTF17bcy    197.058084     +41.600850    2457805.9466    20.23
0.0272      specz
iPTF17bcw    201.468624     +39.173964    2457805.94814   20.65
0.0636      specz
iPTF17bcs    198.456906     +38.894402    2457805.94814   19.60
0.0794      spez; nuclear
iPTF17bcr    200.757880     +40.201309    2457805.9481    20.35
0.0640      specz
iPTF17bcn    201.030920     +42.445651    2457805.95116   19.99
0.079       photz; nuclear
iPTF17bcl    207.110772     +41.975701    2457805.95416   20.44
0.183       photz
iPTF17bck    208.258285     +40.302280    2457805.95715   19.85
?           no photz available
iPTF17bci    209.602490     +43.662936    2457805.95867   19.74
0.065       specz; nuclear
iPTF17bch    209.362268     +44.387701    2457805.95867   19.65
0.072       specz; nuclear?
iPTF17bcg    211.528986     +42.673631    2457805.96015   19.37
0.088       specz
iPTF17bce    212.679949     +37.081015    2457805.96316   20.37
0.224       photz
iPTF17bbv    174.674325     +36.232952    2457805.8986    18.27
0.05996     specz
iPTF17bbu    167.125966     +31.440313    2457805.8911    19.70
0.06        photz
iPTF17bbt    166.948991     +31.255977    2457805.8911    20.02
0.087       photz
iPTF17bbs    166.950771     +31.311975    2457805.8911    19.95
0.072       specz
iPTF17bbq    168.377846     +29.667545    2457805.8911    20.25
0.0455      specz; =PS17bew (GCN 20699
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 )
iPTF17bbp    166.537702     +30.246383    2457805.8911    19.95
0.030       specz
iPTF17bbn    167.184990     +31.218324    2457805.8911    19.29
0.073       specz; also detected 2017-02-17 (g=20.11); nuclear
iPTF17bbg    169.748759     +35.743451    2457805.89411   19.89
0.104       specz
iPTF17bbf    170.901072     +34.765936    2457805.89411   19.60
0.186       photz
iPTF17bbe    170.036330     +34.312810    2457805.89411   20.49
0.037       specz; nuclear (SDSS AGN)
iPTF17bbb    170.475973     +33.961040    2457805.89411   20.11
0.078       photz
iPTF17bba    170.464827     +33.845571    2457805.89411   19.88
0.044       specz
iPTF17baz    170.427019     +34.363034    2457805.89411   19.05
0.035       specz
iPTF17bav    168.441386     +37.278479    2457805.8956    19.61
0.100       specz
iPTF17bat    171.393094     +40.511821    2457805.89712   20.01
0.122       specz
iPTF17baq    134.698013     +01.842508    2457805.78102   19.70
0.058       specz; nuclear?
iPTF17bap    134.438423     +00.933616    2457805.78102   19.80
0.120       specz; nuclear
iPTF17bao    133.976313     +00.853143    2457805.78102   19.41
0.053       specz; nuclear (SDSS AGN)
iPTF17bam    134.670596     +02.078209    2457805.78102   19.88
0.125       specz; rising (0.35 mag intra-night)
iPTF17bal    138.036706     +06.780975    2457805.78255   19.72
0.143       specz; nuclear
iPTF17bak    138.746540     +05.045414    2457805.78404   20.55
0.143       specz; nuclear (SDSS AGN); rising (0.39 mag intra-night)
iPTF17bai    141.156805     +08.409091    2457805.78853   19.97
0.129       specz; nuclear?
iPTF17bah    141.492784     +08.840897    2457805.78853   20.51
0.107       specz; nuclear?; rising (0.59 mag intra-night)
iPTF17bag    137.893562     +06.774493    2457805.78255   20.20
0.225       photz; nuclear
iPTF17bad    141.730214     +08.380390    2457805.78853   19.72
0.122       specz; nuclear?
iPTF17baa    133.693265     +01.183738    2457805.78102   19.46
0.066       photz
iPTF17aas    170.123758     +34.754070    2457805.89411   18.96
0.042       specz; =SN2017aas=PTSS-17dib=PS17bey, known SNIa.
iPTF17mf     214.129450     +39.586295    2457805.96167   17.21
0.0257      specz; =SN2017mf, known SNIa.
iPTF17jg     204.057109     +38.348005    2457805.94963   18.57
0.014       specz; =ATLAS17aic, first discovered 2017-01-09
iPTF17hy     202.138887     +39.486881    2457805.94963   20.18
0.064       specz; =Gaia17abk=PS17hc, first discovered 2017-01-12.

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.

We cross-matched this list to our ongoing effort to build a more complete
Census of the Local Universe (CLU; Cook et al. 2017) by identifying
redshifted Halpha emitters out to 200 Mpc. The hosts of iPTF17bdq,
iPTF17bdl, iPTF17bcy, iPTF17bcn, iPTF17bbe, and iPTF17bbb, are viable
emission line candidates.

We encourage spectroscopic classification of these candidates. In
particular, we highlight iPTF17bec, iPTF17bds, iPTF17bdd, iPTF17bam, and
iPTF17bah as fast-evolving by more than 0.3 mag in the same night. In
addition, our local transients (d < 100 Mpc) are iPTF17jg, iPTF17bdq,
iPTF17bbp, iPTF17bdl, and iPTF17bdd, and our bright transients (R < 19 mag)
are iPTF17bbv, iPTF17jg, iPTF17bdd, iPTF17baz, and iPTF17beb.

Yoshida, M. (Hiroshima U.), Itoh, R., Tachibana, Y., Fujiwara, T.,
Morita, K., Saito, Y., Kawai, N. (Tokyo Tech), Yanagisawa, K.,
Kuroda, D. (OAO, NAOJ) on behalf of J-GEM collaboration

We conducted optical imaging observations of nearby galaxies within
the probability skymap of G274296 (Shawhan et al. GCN20689
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 ) with
the 50cm MITSuME telescopes at Akeno Observatory and Okayama
Astrophysical Observatoty (OAO) and the 91cm wide field near-infrared
camera (OAOWFC) in the framework of J-GEM collaboration. We obtained
optical three color data, g', Rc, and Ic, simultaneously with a
three color camera attached to the MITSuME telescopes. Near-infrared
J-band data were obtained with OAOWFC.

We listed the 5-sigma limiting AB magnitude of each observation below.
No optical/infrared transit source corresponding to the GW event was
found by these observations.


Telescope: Akeno-MITSuME 50cm telescope
----------------------------------------------------------------------
galaxy                  RA      DEC     UT              g'   Rc   Ic
----------------------------------------------------------------------
SDSSJ100438.01+191712.3 151.145 19.2901 2017/2/18-13:22 17.9 17.7 17.2
SDSSJ110234.52+321339.2 165.602 32.3042 2017/2/18-19:31 18.8 18.4 17.4
PGC1754917              157.824 25.9592 2017/2/18-17:58 18.9 18.4 17.5
PGC1752182              157.113 25.8593 2017/2/18-13:46 18.5 18.2 16.9
PGC031387               158.876 26.1942 2017/2/18-20:02 18.2 17.9 16.8
PGC1739538              156.843 25.4675 2017/2/18-11:20 17.9 17.2 16.5
SDSSJ103227.23+254420.0 158.106 25.8022 2017/2/18-16:58 18.8 18.3 17.4
PGC1808655              160.101 27.4668 2017/2/18-14:14 18.5 18.2 17.2
UGC06195                167.267 33.9688 2017/2/18-15:14 16.9 15.3 15.3
PGC1742220              157.981 25.6686 2017/2/18-18:29 18.9 18.4 17.6
PGC1747289              156.049 25.6424 2017/2/18-09:59 17.8 17.2 16.6
SDSSJ105042.23+315119.6 162.700 31.8200 2017/2/18-11:54 18.3 18.0 17.3
SDSSJ095947.63+193539.3 149.959 19.5236 2017/2/18-10:27 18.3 17.7 16.7
PGC029063               150.570 19.1965 2017/2/18-12:21 18.7 18.1 17.5
UGC05403                150.648 19.1695 2017/2/18-12:52 18.9 18.2 17.5
NGC3251                 157.327 26.0998 2017/2/18-14:54 17.5 16.6 16.4
SDSSJ102436.95+253546.9 156.180 25.5393 2017/2/18-10:50 17.4 17.5 16.9
UGC05679                157.205 26.4013 2017/2/19-16:47 16.9 16.6 15.7
SDSSJ102858.64+251713.1 157.240 25.2823 2017/2/19-12:51 18.6 17.9 17.4
UGC05844                160.985 28.1973 2017/2/19-15:56 17.7 17.1 16.3
PGC1758620              157.748 26.0048 2017/2/19-13:23 17.1 17.0 15.8
SDSSJ101200.03+213820.3 153.035 21.5636 2017/2/19-09:50 17.9 17.0 16.4
IC2583                  157.780 26.1222 2017/2/19-16:19 17.0 16.5 15.8
SDSSJ103953.27+272240.0 159.996 27.3349 2017/2/19-11:21 18.6 18.3 17.5
PGC027259               143.837 13.4901 2017/2/19-10:18 18.1 17.7 17.0
SDSSJ100552.60+202338.0 151.437 20.4614 2017/2/19-18:07 16.2 14.6 14.7
PGC028676               149.015 20.5527 2017/2/19-19:09 15.9 14.6 14.7
UGC05401                150.637 18.9816 2017/2/19-10:50 18.3 18.0 18.0
PGC1834191              161.973 28.3977 2017/2/20-14:28 19.2 18.7 17.8
SDSSJ101717.58+220939.3 154.300 22.2234 2017/2/20-16:58 19.2 18.6 17.7
PGC1815236              156.617 27.7584 2017/2/20-19:45 18.4 18.0 16.8
PGC142873               164.106 31.2584 2017/2/20-13:27 19.2 18.5 17.5
SDSSJ103934.08+270302.4 159.907 27.0091 2017/2/20-11:53 16.8 16.3 15.8
IC2590                  159.049 27.0281 2017/2/20-17:30 19.0 18.3 17.5
PGC1793207              156.099 26.9558 2017/2/20-13:57 19.3 18.6 17.7
PGC1752683              157.833 25.8397 2017/2/20-12:26 16.9 16.9 16.2
SDSSJ104414.58+284206.3 161.031 28.7746 2017/2/20-18:32 18.7 18.1 17.3
PGC1662338              154.073 22.0953 2017/2/20-16:28 19.2 18.6 17.6
SDSSJ104053.41+270354.0 160.235 27.0461 2017/2/20-12:56 18.8 18.2 17.4
PGC029111               150.714 20.2397 2017/2/20-14:59 19.0 18.4 17.5
PGC1980945              166.151 32.1969 2017/2/20-19:14 18.3 17.9 16.3
PGC031406               159.008 27.0253 2017/2/20-18:00 18.8 18.3 17.3
----------------------------------------------------------------------

Telescope: OAO-MITSuME 50cm telescope
----------------------------------------------------------------------
galaxy                  RA      DEC     UT              g'   Rc   Ic
----------------------------------------------------------------------
UGC06384                170.492 34.9486 2017/2/18-19:03 19.4 19.5 18.9
SDSSJ094405.52+170156.0 146.023 17.0324 2017/2/18-14:09 19.4 19.3 18.7
SDSSJ093238.79+113551.7 143.162 11.5977 2017/2/18-12:50 19.2 19.1 18.6
SDSSJ092951.83+115535.7 142.466 11.9266 2017/2/18-11:32 18.3 18.5 17.9
SDSSJ092816.16+110437.4 142.067 11.0770 2017/2/18-11:13 18.2 18.4 17.9
PGC2053997              170.195 34.7511 2017/2/18-19:24 19.2 19.1 18.4
PGC1888393              162.717 30.0545 2017/2/18-20:21 18.9 18.9 18.3
PGC142873               164.084 31.2703 2017/2/18-20:02 18.6 19.2 18.5
PGC090923               143.003 12.2616 2017/2/18-11:52 19.2 18.7 18.1
PGC035503               172.781 35.5896 2017/2/18-17:05 19.4 19.3 18.7
PGC032906               164.200 31.0904 2017/2/18-19:42 19.0 19.2 18.5
PGC027259               143.841 13.5489 2017/2/18-13:10 19.4 19.4 18.3
PGC027237               143.732 11.6809 2017/2/18-13:29 19.3 19.2 18.7
PGC027113               143.216 12.2868 2017/2/18-12:31 19.1 19.1 18.6
PGC027081               143.068 12.0939 2017/2/18-12:11 18.9 19.0 18.4
NGC3694                 172.226 35.4139 2017/2/18-17:45 19.4 19.4 18.8
NGC3380                 162.051 28.6018 2017/2/18-20:41 18.7 18.8 18.2
NGC2954                 145.100 14.9226 2017/2/18-13:50 19.3 19.3 18.7
2MASXJ11291265+3523089  172.303 35.3858 2017/2/18-17:25 19.3 19.4 18.8
----------------------------------------------------------------------

Instrument: OAOWFC
-------------------------------------------------------------
galaxy                  RA      DEC     UT              J
-------------------------------------------------------------
UGC05381                150.215 22.3137 2017/2/18-13:08 18.79
SDSSJ100106.15+221806.0 150.276 22.3017 2017/2/18-13:08 18.79
IC2551                  152.668 24.4141 2017/2/18-13:54 18.81
PGC027113               143.216 12.2868 2017/2/18-10:39 18.26
PGC027081               143.068 12.0939 2017/2/18-10:39 18.26
UGC05420                150.995 22.2760 2017/2/18-18:44 18.51
PGC1667794              150.965 22.3239 2017/2/18-18:44 18.51
PGC1667131              150.985 22.2882 2017/2/18-18:44 18.51
PGC1666640              150.995 22.2641 2017/2/18-18:44 18.51
UGC05381                150.215 22.3137 2017/2/18-18:02 18.72
SDSSJ100106.15+221806.0 150.276 22.3017 2017/2/18-18:02 18.72
2MASXJ09532220+2026551  148.343 20.4487 2017/2/18-12:22 18.66
-------------------------------------------------------------

A. Gal-Yam, G. Leloudas, P. Vreeswijk (Weizmann), K. C. Chambers
(IfA), M. E. Huber (IfA), S. J. Smartt, K. W. Smith, D. Wright,
D. Young (QUB), F. Taddia, C. Barbarino, A. Nyholm, C. Fremling,
J. Sollerman (OKC), M. T. Botticella (INAF-Capodimonte), M. Fraser
(UCD), C. Inserra, E. Kankare, K. Maguire, M. Sullivan (Southampton),
S. Valenti (UC Davis), O. Yaron, I. Manulis (Weizmann), E. Cappellaro
(INAF-Padova),, M. Coughlin (Harvard), T.-W. Chen (MPE), L. Denneau,
H. Flewelling, A. Heinze, T. Lowe, E. A. Magnier (IfA), A. Rest
(STScI), B. Stalder, A. S. B. Schultz (IfA), C. W. Stubbs (Harvard)
J. Tonry, C. Waters, R. J. Wainscoat, H. Weiland, M. Willman (IfA) report:


We have reanalysed the spectrum of PS17bek obtained by PESSTO (Taddia
et al. GCN 20708
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 ), an object in the sky map of G274296.  The spectrum
is blue but shows weak broad features and a weak emission line that
was previously identified with Halpha at z=0. The object was therefore
thought to be Galactic.

Cross-correlating the spectrum with supernova template spectra in SNID
(Blondin & Tonry, 2007), we find a good match to the spectra of
super-luminous supernovae (SLSNe type I).  In particular, we find a
good match with the spectra of SN 2010gx at -5 days before peak if
PS17bek is at a redshift of z~0.31. In this context, the weak emission
line at 6559.4 is consistent with [O III] 5007 at z = 0.31, and we
also detect [O III] 4959 at a consistent redshift but lower
significance. The [O III] lines are typically the strongest emission
lines in SLSN dwarf, starforming hosts (Leloudas et al. 2015).  There
is a faint, uncatalogued source in the Pan-STARRS1 3Pi r-band image
which is likely the host at r~23.5 (Chambers et al. arXiv:1612.05560
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 ).

We therefore classify PS17bek as a SLSN I at z = 0.31. 
The Pan-STARRS lightcurve is flat at i=19.8 over two days : 
MJD             mag     filter 
57802.30629	19.85	i	
57804.58218	19.81	i

This indicates that the object is likely close to maximum light
and has a rest frame absolute magnitude of M_r ~ -21.0.

Although these superluminous events are relatively rare by sky
density, they have rise times from explosion to peak of around 20-40
days (e.g. Nicholl et al. 2015). Therefore the explosion probably
occurred at least 20 days before the GW detection of G274296
(57801.254 ; Shawhan et al. GCN20689
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 ) and is likely unrelated.

D. Roberts, M.Morrell & U. Kolb (The Open University) reporting on behalf of the PIRATE group:

We observed 4 separate fields of the G274296 cWB skymap using our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain. We acquired 96 images across the first night of observation, with a further 24 images taken 2 days later, all images were obtained using the R filter and 100s exposure length. Initial observations began at 2017-02-17T23:39:33, approximately 35 minutes after the initial GCN alert was received. A list of the 4 fields observed is given below, each with FoV of 0.7x0.7 degrees centred around the given coordinates. Analysis is ongoing.

Field      RA          Dec
#1:          150.0     20.0
#2:          157.5     25.0
#3:          153.75   22.0
#4:          142.5     15.0
-- The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302). The Open University is authorised and regulated by the Financial Conduct Authority.

The LIGO Scientific Collaboration and Virgo report:

The Coherent WaveBurst event candidate of 2017-02-17, with GraceDB ID
G274296, was initially reported (LSC and Virgo, GCN 20689
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 ) with an
estimated false alarm rate (FAR) of 1.7e-7 Hz, or about 5.4 per year.
Offline re-analysis has not changed this estimate.  At this time, we
do not have any evidence suggesting that the significance of this
event will increase on further study.  Also, the (potential) signal
in the data is inconsistent with a compact binary
coalescence waveform.

A. Smith (UMD) and I. Martinez (UMD) 
report on behalf of the HAWC Collaboration

HAWC was operating and our real-time all-sky GRB monitoring analysis was running at the time of the G274296 event. At the time of the event, the HAWC detector was oriented at (��, ��) = (141.4��, 19.0��), local zenith. 62% of the LIGO/Virgo CWB probability contour fall within our observable field (0-45 deg zenith angle).

We perform a real-time search for counts above the steady-state cosmic-ray background using 4 sliding time windows (0.1, 1, 10, and 100 seconds) shifted forward in time by 10% of their width over the course  of the entire observing period. Within each time window, we search the HAWC sky within 45 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 optimized 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 the gravitational-wave trigger.

After the GW trigger was reported, we re-analyzed the data within �� 60 seconds of the gravitational-wave trigger on 4 timescales (0.1,1, 10, 100 sec) with a reduced threshold to account for the reduced number of trials. No candidates were identified.

Additionally, we searched for longer duration emission by observing the candidate locations beginning from the time of the trigger as they transited the FOV, roughly 3 hrs or half of a full transit for most of the observable contour. This analysis is optimized for ~0.5-100TeV. We found no evidence of emission. The 5-sigma detection sensitivity of this search varies from roughly 1.4-3 x the flux of the Crab.

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. (learn more http://hawc-observatory.org)

M. Moriyama, A. Yoshida, T. Sakamoto, Y. Kawakubo, 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 G274296 (GCN Circ. 20689
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 ).  No CGBM on-board trigger occurred at the time
of the event.  Based on the LIGO localization sky map (skyprobcc_cWB.fits),
the part of the northern 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 1% and 20%.

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 G274296.  However, no LIGO error region was included in the CAL's
field of view at the time of the trigger.

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

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

MASTER continues inspection of LIGO event G274296 (Shawhan et al. GCN 
20689
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 , Lipunov et al. GCN 20696
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 , GCN 20715
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 ; 20712; ). The cover map of 
MASTER inspection survey, 
the 
position of MASTER OTs inside LIGO error-box is presented at 
http://master.sai.msu.ru/static/MASTERGW170217full.jpg

  MASTER OT J184722.28-834543.4 discovery - new optical transients, no 
known sources in VIZIER database.


MASTER-OAFA auto-detection system discovered OT source at (RA, Dec) = 18h 
47m 22.28s -83d 45m 43.4s on 2017-02-24.13990 UT with unfiltered 
m_OT=17.6m (mlimit=19.4m).

The OT is seen in 2 images. There is no minor planet at this place.

We have reference images without OT on 2017-01-26.20851 UT with 19.7m 
unfiltered magnitude limit in MASTER-OAFA, on 2016-08-05 18:16:52UT with 
mlim=19.5, on 2016-03-02 23:53:05 with mlim=20.0, 2015-04-26 23:34:52 with 
mlim=20.0, on2015-01-12 01:41:57UT with mlim=19.6 in MASTER-SAAO database.

There is no any known sources inside 8" in VIZIER database, it means 22mag 
of POSS historical limits and more then 4.4magnitude of current outburst 
amplitude.

Spectral observations are required.

The discovery and reference images are available at: 
http://master.sai.msu.ru/static/OT/184722.28-834543.4.png

From C.M. Copperwheat (LJMU), A.S. Piascik (LJMU) and I.A. Steele (LJMU) on
behalf of a larger collaboration.

We report the following Liverpool Telescope follow-up observations of EM
candidates. Observations were made with the SPRAT spectrograph, and
supernova classifications were obtained using SNID (Blondin & Tonry, 2007,
ApJ, 666, 1024).

iPTF17bam was observed on 2017-02-22 at 23:04UT. The transient is centrally
located within its host galaxy and the spectrum is indicative of an AGN.

iPTF17bds was observed on 2017-02-24 at 04:36UT. We classify this transient
as a type Ia SN at +8 days with z=0.203.

PS17bfg was observed on 2017-02-24 at 03:46UT. We classify this transient
as a type Ia SN at +15 days with z=0.140. The galaxy 2MASX
J11453974+3323354 at a separation of 0.064 arcmin has catalogue z=0.141258.

PTSS17gpm was observed on 2017-02-24 at 05:02UT. We classify this transient
as a type Ia SN at +1 days with z=0.080.

iPTF17beb was observed on 2017-02-24 at 05:53UT. We classify this transient
as a type II SN at +17 days with z=0.056.


We also observed the following targets. In these targets the spectrum seems
to be dominated by the host galaxy and we see no evidence of a transient
above the host galaxy emission in the acquisition images. In the majority
of cases the transient coordinates are very close to the centre of the host
galaxy.

iPTF17bah was observed on 2017-02-23 at 00:33UT.
iPTF17baz was observed on 2017-02-24 at 01:07UT.
PS17bfc was observed on 2017-02-24 at 02:04UT.
iPTF17bdl was observed on 2017-02-24 at 02:44UT.
iPTF17bdd was observed on 2017-02-24 at 03:41UT.
iPTF17bec was observed on 2017-02-24 at 05:33UT.

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

We carried out observations of LIGO/Virgo G274296 (LVC, GCN 20689
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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 2017-02-19 starting at 01:21:55 UT relatively good sky conditions.
The covered area captured a containment probability of ~5%  and was chosen to maximize the number of local (< 30 Mpc) galaxies to be observed.
The area is divided in 4 blocks of 3x3 pointing each of them of covering 1.15x1.15 square degrees of the sky and 5x90 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 and relative density of nearby galaxies.

The pointings are centered on the following UT times, coordinates RA, Dec (J2000) and observed area:

2017-02-19T21:22:04      137.106      5.926      1.15x1.15 square degrees
2017-02-19T04:16:28      166.43       28.33       1.15x1.15 square degrees      
2017-02-19T04:10:14      162.47       28.01       1.15x1.15 square degrees

3x3 pointing blocks
2017-02-19T02:54:33      157.481     28.318      ~3x~3 square degrees
2017-02-19T01:21:55      157.34       23.988      ~3x~3 square degrees
2017-02-19T23:35:11      157.22       20.9          ~3x~3 square degrees
2017-02-19T21:33:26      153.709     21.68        ~3x~3 square degrees

The limiting magnitude is r ~ 20.5. Analysis of images is ongoing.
-- 
Enzo Brocato
INAF - Osservatorio Astronomico di Roma
Via di Frascati 33,  
I-00040 Monteporzio Catone, Italy
Phone:  +39 0694286438 Fax: +39 06 9447243
skype: enzo.brocato
URL: SpoT Group Homepage: www.oa-teramo.inaf.it/SPoT

D.M. Palmer (LANL), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),
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 $B!^(B 100 s of the
LIGO event G274296 (LIGO/VIRGO Collaboration GCN Circ. 20689
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 ),
where T0 is the LIGO trigger time (2017-02-17T06:05:55.050 UTC).

The BAT pointing position at T0 is
RA = 133.700 deg,
DEC =  20.061 deg,
ROLL = 319.960 deg.
The BAT Field of View (>0.1 partial coding) covers 65.49% of the integrated
LIGO localization probability.

The closest event data covers the time range from T0-26.67 to T0-23.61,
and from T0+48.33 to T0+134.46. No sources with signal-to-noise ratio > 6 sigma
are found in these event data.

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 ~ 6.9 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 17.86% 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.

R. Lunnan (Caltech), D. Cook (Caltech), K. De (Caltech) and M. M. Kasliwal
(Caltech)

report on behalf of the iPTF and GROWTH collaborations

Under cloudy and windy weather conditions, the following classification
spectra were obtained with the Palomar 200-in telescope using the DBSP
spectrograph (Oke & Gunn, 1982, PASP, 94, 586).

ATLAS17aic (=iPTF17jg) was observed on 2017-02-23 13:03 UT. The spectrum
shows strong galaxy emission lines at z=0.013 and a broad P-cygni Halpha
profile, consistent with a Type II SN a few weeks after maximum light.

PS17bew (=iPTF17bbq) was observed on 2017-02-23 10:33 UT . The spectrum
shows broad Halpha emission, consistent with a Type II SN, confirming the
classification reported by PESSTO (ATel #10127).

iPTF17bdd was observed on 2017-02-23 11:48 UT. The spectrum is dominated by
galaxy light, as was also the case in the spectrum reported from Liverpool
Telescope (LVC GCN #20734
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 ).

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

D.Buckley,
  South African Astronomical Observatory

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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

MASTER OT J072511.84-881702.0 discovery - PSN in cluster's galaxy

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )
  discovered OT source at (RA, Dec) = 07h 25m 11.84s -88d 17m 02.0s on 
2017-02-22.81740 UT.

The OT unfiltered magnitude is ~19.0m (mlim=20.2).
The OT is seen in 4 image. There is no minor planet at this place.

This PSN is in 12" from bright galaxy (USNO B1 0017-0004125, 
B2=15.9,R2=15.3). There is a cluster of galaxies in this area.

We have reference image on 2015-04-15.98271 UT with  unfiltered m_lim= 
20.6m.

Spectral observations are required.

http://master.sai.msu.ru/static/OT/MASTEROTJ072511.84-881702.0.jpg

S. Sugita, N. Kawai (Tokyo Tech), M. Serino (RIKEN), 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
G274296 at 2017-02-17 06:05:55.050 UTC (GCN 20689
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 ) and
G275404 at 2017-02-25 18:30:21.374 UTC (GCN 20738
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 ).

MAXI/GSC did not observe (HV off) at the trigger time of G274296,
and observed from T0+843 sec.
MAXI/GSC scanned more than 87%
of the whole sky in the 92-min orbit, which includes 77.4% of the
90% regions in the skyprobcc_cWB skymap.
One day image covers 89.7% of the 90% regions
in the skyprobcc_cWB 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 one-day images are
40 (120) mCrab and 15 (35) mCrab, respectively,
which was larger than the typical upper limits of GSC
because anti-coincidence function of one of the GSC cameras was disabled.

In G275404 observation,
MAXI/GSC did not observe at the trigger time
and observed from T0+1246 sec.
MAXI/GSC scanned more than 62%
of the whole sky in the one orbit, which includes 55.0% of the
90% regions in the bayestar skymap.
One day image covers 96.3% of the 90% regions
in the bayestar skymap.
No significant new source was found in these images.
For instance, typical 2-20 keV 1-sigma (3-sigma) upper limits obtained
from the one-orbit and one-day images are
12 (36) mCrab and 3 (9) mCrab, respectively.

MAXI/GSC also observed the position of the possible gamma-ray
transient (GCN 20754
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 ),
but it was difficult to estimate upper limits because the effect of stray photon
from bright GRS 1915+105 near by the localized position of the transient
was large.

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

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas de la Tierra y del Espacio (ICATE),
San Juan, Argentina

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

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, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

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


MASTER-OAFA (Argentina) auto-detection system discovered  MASTER OT 
J042250.16-820415.4 as bright OT
  at (RA, Dec) =  04 22 49.70 -82 04 10.0  on 2017-02-19.12023UT  during 
inspection (Lipunov et al. GCN 20696
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 , GCN 20711
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 )
  of LIGO/VIRGO G274296 event (Peter Shawhan, GCN 20689
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 ) 
http://master.sai.msu.ru/static/OT/MASTEROTJ042250.16-820415.4.jpg  .

This SN is located near the maximal probability area of southern part of 
this GW event error-box.

MASTER-SAAO started inspection of this SN every night with W,B,I,R and V 
filters (21 nights at this moment).
We have good accuracy of its photometry, i.e. the detailed registered 
WBIRV light curve before and during its maximum. "W" - is the unfiltered.

This SN is in 2.6E,11.9N offset from the center of galaxy with low surface 
brightness ESO015-010 (PGC014998) with Btc =16.54m
and Bri25=24.63m (mean surface brightness within 25th-mag isophote).

On the 25th of Feb 2017 PESSTO detected its type (Ia) and z=0.02 (Nyholm 
et al. ATel #10131)

We carried out a preliminary joint analysis of the light curves of 
MASTER OT J042250.16-820415.4 with respect to  supernovae of the similar 
brightness in order to determine the time of explosion of this supernova.

Figure  http://master.sai.msu.ru/static/MASTEROTJ042250.16-820415.4.png 
shows that   MASTEROTJ042250.16-820415.4
supernova reach maximum brightneses ~ 15 days after LIGO G274296 trigger. 
This fact shows that the SN explosion time is very close to the LIGO 
G274296  trigger and this SN could be the progenitor of this event.

The    ESO 15-10 galaxy photometrical distance  is about 84.6 Mpc  for 
Omega_Lambla=0.7+-0.1, Omega_tot=1 an H=72+/-2 km/s/Mpc. The maximal 
magnitute in B filter is about

M(B) = -19.5+/-0.1

The error  include the uncertainty of the cosmological parameters.
This is preliminary analysis of the observations.
Recently one of us  noted  that double O-Ne-Mg white dwafs merging can be 
produce powerfull non spiralling waveform gravitational waves  for 
LIGO/VIRGO type interferometers (Lipunov V.M.,   arXiv: AstroPh, 
submission number 1830243; will be appear
13.03.2017; submitted to New Astronomy).

So we conclude that SNIa MASTER OT J042250.16-820415.4 in ESO 15-10 galaxy 
is the real optical counterpart  of the  gravitational 
waves event LIGO/Virgo G274296 .

All observations are required.

Sheng Yang (INAF-OAPd, UC Davis), Stefano Valenti(UC Davis), David Sand (TTU), Leonardo Tartaglia (TTU, UC Davis), Enrico Cappellaro(INAF-OAPd), Dan Reichart, Josh Haislip (UNC) report on behalf of the Gravitational Wave Follow-Up by DLT40.

We report the observation of 25 galaxies within the LVC error region for the GW trigger G274296 using the cWB localization map.We selected 46 galaxies from the GWGC catalogue within 80.0% of the trigger error region, within a distance of 40.0 Mpc, brighter that -17.5 mag and at a Declination < 20 degree. 25 of those galaxies have been observed using the Prompt 5 telescope and are part of the ongoing DLT40 search. They represent the 1.3% of all galaxies within 40.0 Mpc in the Glade catalogue within the LVC error region for the GW trigger and contains 6.1% of all B band luminosity of those galaxies. We started to observe these sample of galaxies on 2017-2-17 and monitored them for 3 weeks after the GW trigger. No interesting transients have been identified down to a limit magnitude of 18.5.

Below follow the list of galaxies observed:
Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG
IC2367 126.042 -18.7755 29.18 -20.71 -23.8874
NGC2775 137.5837 7.0379 17.3 -20.17 -24.1532
NGC3041 148.2798 16.6777 23.77 -19.86 -23.1421
PGC023658 126.4918 -11.7792 38.93 -19.84 -21.7084
NGC2695 133.6128 -3.067 32.36 -19.76 -23.695
PGC024778 132.2517 -7.8298 38.02 -19.75 -22.3331
NGC2894 142.3758 7.7179 30.49 -19.75 -23.3068
NGC2722 134.6925 -3.71 38.02 -19.68 -22.4881
NGC3226 155.8624 19.8984 23.55 -19.59 -23.29
NGC2919 143.6982 10.2837 34.67 -19.54 -22.6498
NGC2906 143.026 8.4419 29.92 -19.28 -23.2668
NGC3020 147.5274 12.8136 21.88 -19.2 -21.0172
NGC2708 134.0337 -3.36 26.55 -19.15 -23.2403
PGC023723 126.892 -12.7566 34.61 -19.08 -21.689
UGC05467 152.0539 18.7071 39.71 -18.96 -22.1495
NGC3024 147.6141 12.7655 25.35 -18.92 -20.8419
NGC2698 133.9023 -3.1838 24.94 -18.89 -23.1405
IC0540 142.5429 7.9027 28.64 -18.75 -21.7699
NGC2690 133.1584 -2.6032 21.04 -18.61 -21.9722
NGC2697 133.7475 -2.9876 24.17 -18.59 -22.0234
NGC2612 128.4585 -13.1747 21.67 -18.59 -22.9033
UGC04684 134.1696 0.375 35.67 -18.54 -20.5195
NGC2706 134.0512 -2.5634 21.88 -18.48 -22.1752
UGC05403 150.6481 19.1769 33.42 -18.48 -22.284
UGC04845 138.1077 9.9555 30.18 -18.33 -20.6846

The LIGO Scientific Collaboration and Virgo report:

We have performed the off-line analysis of the LIGO data around
the time of the burst event G274296 using the Coherent WaveBurst
(Klimenko et al., PRD 93, 042004 (2016)) with a better estimation
of the background. The new estimated FAR is one event in 6 months.
The low significance of this candidate is not expected to improve
with further analysis.

An updated localization,  skyprobcc_cWB_170629.fits, is available for
retrieval
from the GraceDB event page:

https://gracedb.ligo.org/events/G274296

This is the preferred sky map at this time. The localization is consistent
with the previous sky map, however, its error region is smaller due to
improved
calculation of the coherent Waveburst skymaps for the low SNR events.
The 50% credible region spans 245 deg2 and the 90% credible region spans
1153 deg2.

Further updates on our analysis of this event will be sent as they become
available.

[GCN OPS NOTE(29jun17):  Per adminstrator's request, the author-generated
5-line title block was removed, leaving only the GCN-generated 5-line title block.]