LIGO/Virgo G275404

S.-W. Chang, A. M�ller, C. A. Onken, C. Wolf (ANU) report on behalf of the SkyMapper Transient follow-up collaboration:
We had carried out follow-up observations of the LIGO/Virgo G275404 and (LVC, GCN 20738
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 ) and G275697 (LVC, GCN 20763
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 ) with the SkyMapper 1.35-m telescope on the night of 2017-02-27 UTC and 2017-03-01/2017-03-05 UTC, respectively. Our imaging fields were automatically selected to encompass 60% of the probability region of the southern sky provided by LIGO collaboration at the time of the alert.

The coverages of the observed fields are similar but slightly larger than the REM follow-up observations (Chile). For the first alert, we obtained 20 fields (~120 sq. degrees) at least twice in r filter. Delayed observations are due to bad sky conditions. We used our transient survey pipeline to discover candidate variable sources in difference images by implementing a machine-learning classifier (Scalzo et al. 2017). Except for candidate variable sources previously registered in the SkyMapper Transient Database (https://www.mso.anu.edu.au/skymapper/smt/), we found a new Type Ia supernova (SN 2017bzt) that was spectroscopically classified by the PESSTO collaboration:
TNSname, Name, RA, DEC, Type, Redshift, Note

SN 2017bzt, SMTJ13030970-3925172, 195.790404899, -39.421452087, SN Ia, 0.11, offset 2.76" from GALEXASC J130309.82-392514.3 (https://wis-tns.weizmann.ac.il/object/2017bzt).
 And for the G275697 alert, 40 fields (~228 sq. degrees) were observed once or twice in ri filters over two observations on 2017-03-01 and 2017-03-05 UTC. Except for candidate variable sources previously registered in the SkyMapper Transient Database, we did not see any significant transient sources from the observed fields. One known Type II Supernova detected by ATLAS on 2017-02-19 was recovered with SkyMapper (SMT17bgo):
TNSname, Name, RA, DEC, Type, Redshift, Note
SN 2017blh, SMTJ10521059-2747516, 163.044138303, -27.7976683704, SN II, 0.0334, discovered by ATLAS (https://wis-tns.weizmann.ac.il/object/2017blh).

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), G. Hosseinzadeh, I. Arcavi, D. A. Howell, C. McCully (Las Cumbres Obs./UCSB) report on behalf of the Gravitational Wave Follow-Up by DLT40.

We report the observation of 50 galaxies within the LVC error region for the GW trigger G275404 using the 'bayestar' GW localization map from 2017-2-26 to 2017-3-9. Starting from 2017-3-9 (until 2017-3-12) we observed 84 galaxies using the update LALInference localization map. We selected galaxies from the GWGC catalogue within 80.0% of the trigger error region, within a distance of 40.0 Mpc, brighter than -17.5 mag and at a Declination < 20 degree.
Those selected galaxies have been observed using the Prompt 5 telescope and they are part of the ongoing DLT40 search. The first 50 galaxies represent the 3.9% of all galaxies in the Glade catalogue within 40.0 Mpc and within the LVC error region for the GW trigger. They also contain 12.7% of all B band luminosity of those galaxies.
The 84 galaxies, observed after 2017-3-9, represent the 1.5% of all galaxies and contains 9.7% of all B band luminosity.
The DLT40 search limit magnitude, for those galaxies is 19.2 (open filter scaled to r band). We found one SN Ia, SN2017cbv/DLT17u, in NGC5642 on 2017-3-8, which is only 16 Mpc away.
Our follow-up observations of SN2017cbv/DLT17u with Las Cumbres Observatory telescopes show that SN2017cbv/DLT17u has recently reached its maximum luminosity (Bmag ~ 11.79) 17.7 days after discovery. Giving the typical rise time of SNe Ia (18.98 �� 0.54 days, Firth, R. E., et al. 2014, MNRAS 446, p.3895-3910), SN2017cbv was discovered very close to explosion and we can then exclude that SN2017cbv is related to the GW event that occurred ~ 2 weeks before the explosion epoch of SN2017cbv.

Below follow the list of galaxies observed:
Name RA(J2000) DEC(J2000) Dist(Mpc) BMAG KMAG OBS_WINDOW(JD)
ESO176-006 224.29 -54.39 38.01 -21.5 -24.4 2457821.57-2457825.39
NGC4696 192.20 -41.31 35.48 -21.4 -25.6 2457821.57-2457825.39
ESO380-006 183.89 -35.62 38.93 -21.3 -24.7 2457821.57-2457825.39
NGC6384 263.10 7.0603 25.94 -21.2 -24.5 2457821.57-2457825.39
NGC3962 178.66 -13.97 35.32 -21.2 -25.0 2457821.57-2457825.39
NGC5078 199.95 -27.41 27.67 -21.2 -25.0 2457821.57-2457825.39
NGC4603 190.23 -40.97 33.11 -21.2 -24.2 2457821.57-2457825.39
NGC5643 218.16 -44.17 18.45 -21.1 -24.1 2457821.57-2457825.39
NGC5266 205.75 -48.16 38.02 -21.1 -25.4 2457821.57-2457825.39
IC3253 185.93 -34.62 34.67 -21.0 -23.5 2451870.67-2457825.39
NGC3706 172.43 -36.39 38.02 -21.0 -24.9 2457821.57-2457825.39
NGC6574 272.96 14.981 38.91 -20.9 -24.5 2457821.57-2457825.39
NGC3923 177.75 -28.80 22.91 -20.9 -25.3 2451870.67-2457825.39
NGC3338 160.53 13.747 24.43 -20.9 -23.8 2457821.57-2457825.39
NGC5156 202.18 -48.91 36.98 -20.9 -24.1 2457821.57-2457825.39
ESO320-026 177.45 -38.78 38.02 -20.9 -24.2 2457821.57-2457825.39
NGC4976 197.15 -49.50 17.3 -20.9 -24.3 2457821.57-2457825.39
ESO271-022 213.37 -45.41 38.14 -20.8 -23.1 2457821.57-2457825.39
NGC6555 271.95 17.604 33.42 -20.8 -22.7 2457821.57-2457825.39
IC2977 178.81 -37.69 39.01 -20.8 -23.8 2457821.57-2457825.39
NGC5061 199.52 -26.83 24.21 -20.8 -24.6 2457821.57-2457825.39
IC4351 209.47 -29.31 27.54 -20.8 -24.1 2457821.57-2457825.39
NGC3749 173.97 -37.99 38.02 -20.8 -24.1 2457821.57-2457825.39
NGC3672 171.26 -9.795 23.66 -20.7 -23.6 2457821.57-2457825.39
NGC3585 168.32 -26.75 20.05 -20.7 -24.8 2457821.57-2457825.39
NGC5266A 205.15 -48.34 38.02 -20.7 -22.2 2457821.57-2457825.39
ESO442-026 193.05 -29.84 34.94 -20.7 -24.2 2457821.57-2457825.39
NGC5101 200.44 -27.43 24.21 -20.6 -24.7 2457821.57-2457825.39
ESO269-057 197.51 -46.43 36.98 -20.6 -24.0 2457821.57-2457825.39
NGC4373A 186.40 -39.31 37.33 -20.6 -24.0 2457821.57-2457825.39
PGC086291 282.99 11.876 38.02 -20.6 -24.0 2451870.67-2457825.39
NGC4444 187.15 -43.26 36.98 -20.6 -23.4 2457821.57-2457825.39
PGC054411 228.64 -52.98 19.36 -20.6 -24.2 2457821.57-2457825.39
NGC5688 219.89 -45.01 30.9 -20.5 -24.1 2457821.57-2457825.39
IC4214 199.42 -32.10 28.84 -20.5 -24.0 2457821.57-2457825.39
NGC3742 173.88 -37.95 38.61 -20.5 -24.2 2457821.57-2457825.39
NGC4112 181.78 -40.20 34.67 -20.5 -23.4 2457821.57-2457825.39
ESO221-010 207.73 -49.05 38.02 -20.5 -23.6 2457821.57-2457825.39
NGC3904 177.30 -29.27 28.31 -20.5 -24.5 2451870.67-2457825.39
NGC4219 184.11 -43.32 20.99 -20.5 -23.5 2457821.57-2457825.39
NGC3783 174.75 -37.73 38.02 -20.5 -24.2 2457821.57-2457825.39
ESO320-031 178.52 -39.86 38.18 -20.4 -24.8 2457821.57-2457825.39
ESO385-030 217.33 -33.45 34.33 -20.4 -24.0 2457821.57-2457825.39
NGC5219 204.67 -45.85 36.98 -20.4 -22.8 2457821.57-2457825.39
NGC2992 146.42 -14.32 28.84 -20.3 -23.7 2457821.57-2457825.39
NGC4767 193.47 -39.71 32.81 -20.3 -24.3 2457821.57-2457825.39
ESO175-005 214.44 -52.83 37.36 -20.3 -20.2 2457821.57-2457825.39
IC3370 186.90 -39.33 26.79 -20.3 -24.2 2457821.57-2457825.39
ESO380-019 185.50 -35.79 38.02 -20.3 -24.2 2451870.67-2457825.39
PGC046029 198.58 -46.12 36.98 -20.3 -24.3 2457821.57-2457825.39
NGC5063 199.60 -35.35 33.39 -20.3 -23.2 2457821.57-2457825.39
NGC5365 209.46 -43.93 32.36 -20.3 -24.6 2457821.57-2457825.39
ESO321-025 185.42 -39.76 29.38 -20.3 -22.5 2457821.57-2457825.39
NGC4947 196.33 -35.33 27.8 -20.3 -23.1 2451870.67-2457825.39
NGC5085 200.07 -24.44 24.21 -20.3 -22.9 2457821.57-2457825.39
NGC4105 181.67 -29.76 26.55 -20.3 -24.5 2451870.67-2457825.39
NGC3169 153.56 3.4664 18.45 -20.3 -24.0 2457821.57-2457825.39
ESO221-014 208.02 -48.17 35.81 -20.2 -23.1 2457821.57-2457825.39
NGC5365A 209.16 -44.00 36.98 -20.2 -24.0 2457821.57-2457825.39
ESO221-025 211.89 -48.39 38.93 -20.2 -19.4 2457821.57-2457825.39
ESO320-030 178.29 -39.13 38.02 -20.2 -23.6 2457821.57-2457825.39
NGC3459 163.68 -17.04 31.61 -20.2 -22.4 2451870.67-2457825.39
NGC2967 145.51 0.3365 29.92 -20.2 -23.4 2457821.57-2457825.39
IC4197 197.01 -23.79 34.1 -20.2 -23.3 2457821.57-2457825.39
NGC4304 185.55 -33.48 34.67 -20.2 -23.6 2451870.67-2457825.39
ESO377-024 168.13 -36.42 38.21 -20.2 -22.9 2457821.57-2457825.39
NGC4835 194.53 -46.26 20.14 -20.2 -23.3 2457821.57-2457825.39
NGC5483 212.60 -43.32 24.21 -20.2 -23.4 2457821.57-2457825.39
IC4444 217.91 -43.41 25.35 -20.2 -23.4 2457821.57-2457825.39
ESO507-032 193.06 -26.30 20.82 -20.2 -22.3 2457821.57-2457825.39
NGC6570 272.78 14.093 33.42 -20.2 -22.7 2457821.57-2457825.39
NGC5188 202.86 -34.79 28.84 -20.2 -23.7 2457821.57-2457825.39
NGC4993 197.44 -23.38 33.81 -20.2 -23.4 2457821.57-2457825.39
NGC5494 213.1 -30.64 31.19 -20.1 -23.4 2457821.57-2457825.39
NGC3368 161.69 11.819 10.47 -20.1 -23.7 2457821.57-2457825.39
ESO221-020 209.59 -48.47 38.29 -20.1 -23.6 2457821.57-2457825.39
ESO321-016 183.86 -38.14 38.02 -20.1 -21.9 2457821.57-2457825.39
ESO380-050 189.58 -35.61 38.02 -20.1 -20.5 2451870.67-2457825.39
NGC3115 151.30 -7.718 10.33 -20.1 -24.1 2457821.57-2457825.39
IC0764 182.55 -29.73 21.18 -20.1 -21.9 2451870.67-2457825.39
ESO221-026 212.09 -47.97 20.31 -20.1 -23.9 2457821.57-2457825.39
NGC4462 187.33 -23.16 23.12 -20.1 -23.3 2457821.57-2457825.39
ESO386-039 224.10 -37.60 36.98 -20.1 -22.8 2457821.57-2457825.39
ESO221-012 207.88 -48.08 38.02 -20.1 -21.9 2457821.57-2457825.39
PGC033108 164.90 -15.52 35.63 -20.0 -21.2 2451870.67-2457821.57
ESO441-017 182.78 -31.12 24.24 -19.9 -21.0 2451870.67-2457821.57
NGC3321 159.71 -11.64 33.88 -19.8 -22.1 2451870.67-2457821.57
NGC3044 148.42 1.5796 21.68 -19.8 -22.6 2451870.67-2457821.57
NGC3885 176.69 -27.92 21.88 -19.7 -23.3 2451870.67-2457821.57
IC0630 159.64 -7.170 25.85 -19.7 -23.4 2451870.67-2457821.57
ESO324-044 204.52 -39.84 34.51 -19.7 -21.8 2451870.67-2457821.57
NGC3511 165.84 -23.08 12.25 -19.6 -22.3 2451870.67-2457821.57
IC2627 167.47 -23.72 24.21 -19.6 -22.9 2451870.67-2457821.57
NGC5121 201.19 -37.68 20.8 -19.5 -23.1 2451870.67-2457821.57
NGC3936 178.08 -26.90 18.62 -19.5 -22.2 2451870.67-2457821.57
NGC3055 148.82 4.27 25.35 -19.5 -22.5 2451870.67-2457821.57
NGC3375 161.75 -9.941 28.87 -19.5 -22.5 2451870.67-2457821.57
IC3015 182.25 -31.51 24.21 -19.5 -23.1 2451870.67-2457821.57
IC2995 181.44 -27.94 16.75 -19.4 -21.8 2451870.67-2457821.57
ESO381-029 194.11 -36.37 29.54 -19.3 -22.6 2451870.67-2457821.57
ESO569-014 162.85 -19.89 24.77 -19.3 -20.9 2451870.67-2457821.57
IC0760 181.47 -29.29 25.37 -19.2 -22.6 2451870.67-2457821.57
IC3010 181.98 -30.33 25.87 -19.2 -22.8 2451870.67-2457821.57
ESO440-011 177.19 -28.29 21.88 -19.2 -18.0 2451870.67-2457821.57
NGC3673 171.30 -26.73 17.38 -19.2 -22.6 2451870.67-2457821.57
NGC3361 161.12 -11.20 24.21 -19.1 -21.8 2451870.67-2457821.57
ESO440-038 180.42 -31.70 26.65 -19.1 -22.0 2451870.67-2457821.57
UGC05347 149.31 4.5269 29.92 -19.0 -20.2 2451870.67-2457821.57
IC3005 181.80 -30.02 24.32 -19.0 -21.9 2451870.67-2457821.57
ESO440-049 181.39 -31.42 24.24 -18.9 -20.1 2451870.67-2457821.57
ESO440-027 178.35 -28.55 18.53 -18.9 -21.7 2451870.67-2457821.57
NGC3617 169.46 -26.13 25.61 -18.9 -22.2 2451870.67-2457821.57
ESO504-028 178.72 -27.25 22.24 -18.8 -20.2 2451870.67-2457821.57
ESO440-004 176.42 -28.36 22.93 -18.8 -18.4 2451870.67-2457821.57
UGC05376 150.11 3.3744 29.92 -18.8 -22.5 2451870.67-2457821.57
ESO381-038 195.02 -34.43 28.37 -18.7 -20.3 2451870.67-2457821.57
PGC032091 161.29 -10.06 27.64 -18.6 -20.1 2451870.67-2457821.57
ESO441-014 182.55 -30.07 24.67 -18.6 -19.5 2451870.67-2457821.57
IC2996 181.45 -29.97 21.88 -18.4 -20.6 2451870.67-2457821.57
PGC031979 160.90 -9.856 24.21 -18.3 -19.8 2451870.67-2457821.57
ESO441-012 182.36 -32.51 24.21 -18.2 -21.7 2451870.67-2457821.57
ESO440-037 179.82 -28.90 22.99 -18.2 -20.9 2451870.67-2457821.57
ESO324-023 201.87 -38.17 14.26 -18.2 -19.1 2451870.67-2457821.57

The LIGO Scientific Collaboration and Virgo report:

We report an update on the significance of the gravitational-wave trigger
G275404 (GCN 20738
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 ). This trigger was reported by the online PyCBC search
with a false alarm rate (FAR) of 6 per year; i.e. background noise in the
detectors produces 6 triggers per year as loud as G275404 in the PyCBC
low-latency search. This trigger had low significance, but passed the FAR
threshold of ~ 1 / month for generating an alert.

We have completed the offline search over the time containing G275404 using
the PyCBC (Usman et al. 2016, CQG 33, 215004) and GstLAL (Messick et al.
2016, PRD 95, 042001) searches. These offline analyses provide the final
significance for candidate events.

Neither search produced a significant trigger at the time of G275404. We
conclude that G275404 is not a trigger of interest and does not warrant
further follow-up.

Zsolt Paragi (JIVE)
Tao An (Shanghai Astronomical Observatory)
Philippe Bacon (APC Universite�� Paris Diderot)
Rob Beswick (JBO-Manchester University)
Eric Chassande-Mottin (APC Universite�� Paris Diderot)
Sa��ndor Frey (Konkoly Observatory)
Marcello Giroletti (IRA-INAF)
Peter Jonker (SRON)
Mark Kettenis (JIVE)
Benito Marcote (JIVE)
Arpad Szomoru (JIVE)
Huib van Langevelde (JIVE)
Jun Yang (Onsala Space Observatory)
for the Euro VLBI team

We observed the near-IR transient (Yoshida et al., GCN 20784
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 ) within
the error circle of AGL J1914+1043 (Tavani et al., GCN 20754
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 ) with
the real-time very long baseline interferometry (e-VLBI) technique
using the EVN at 4.9 GHz between 2:06���11:48 UT on 24 March 2017.
There is no compact radio emission detected on milliarcsecond scales
within +-4 arcseconds of the near-IR transient coordinates of
RA=19:10:31.46, DEC=+07:53:52.0, with a 6 sigma upper limit of
105 microJy/beam.

More details on the Euro VLBI team observations:
Participating EVN telescopes were Effelsberg, Irbene, Jodrell Bank MkII,
Medicina, Onsala, Noto, Torun, Westerbork (single dish), Yebes,
Arecibo, Hartebeesthoek and Tianma. The observing frequency of 4.9 GHz
was preferred over 1.6 GHz because of strong scatter-broadening in
this region. The phase-referencing calibrator was J1922+0841, 3 degrees
away from the target; it has resolved structure on mas scales, but
strong fringes were detected. The cycle time was 1:30-3:30 minutes.
Total on-source integration time on the target was 4.1 hours.
A number of other calibrators/calibrator candidates were observed
as well, most notably J1909+0756 (11 arcminutes from the target),
that was detected as a ~30 mJy but quite resolved source (~10 mas
East-West; not useful as calibrator beyond 10 Mlambda at this frequency).
None of the sources reported by Medicina single dish observations at
5 GHz (Pilia et al., GCN 20869
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 ) were detected (we had 3 times 1-minute
scans on each). The data were correlated real-time with the
EVN Software Correlator at JIVE (SFXC) and processed according to
standard procedures, using measured system temperature for most
telescopes (for Arecibo, Noto, Jodrell Bank we used nominal SEFDs).

The EVN is a joint facility of independent European, African, Asian,
and North American radio astronomy institutes. Scientific results
from data presented in this publication are derived from the following
EVN project code: RP027.

S. M. Adams, J. Jencson, K. Burdge, N. Blagorodnova, M. M. Kasliwal
(Caltech) and F. Taddia (OKC)

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

On UT 2017-03-07 and 2017-03-16, we spectroscopically classified the
following iPTF optical transient candidates (LVC GCN#20790
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 ) using the
Double Beam Spectrograph (Oke & Gunn 1982) on the Palomar 200-inch Hale
Telescope. All spectra were reduced using the pyraf-dbsp pipeline (Bellm &
Sesar 2016) and spectral matching done using SNID and Superfit.

Name, Redshift, Classification, Notes
(2017-03-07)
iPTF17bps, z=0.109, SN Ia, best match is SN2006ev at +11d
iPTF17bpt, z=0.785, AGN  (but see LVC GCN # 20814)

(2017-03-16)
iPTF17bru, z=0.103, SN Ia, best match is SN1989B +13d
iPTF17bsi, z=0.031, SN II, best match is SN2004dj +0d  (consistent with LVC
GCN # 20814)

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

Following the LIGO/VIRGO event G275404, we performed radio C-band (5 GHz)
single-dish imaging centered at the position of the infrared transient
candidate detected by the Kanata Telescope HONIR camera at RA=19:10:31.46,
DEC=+07:53:52.0 (Yoshida et al. GCN 20784
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 ), placed at the edge of the
Galactic Bubble N82, seen in IR by Spitzer (Churchwell et al., 2006, ApJ,
649, 759). This source was within the error box of the transient candidate
found in the AGILE-GRID data, AGL J1914+1043 (Tavani et al. GCN 20754
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 ).

The observations were performed using the 32-m Medicina radio telescope on
2017-03-06 UT. We detected a bright radio source at the center of the
observed field of 1 x 1 deg. The source appears slightly larger than the
7.4 arcmin beam of the receiver. The flux density at 5 GHz was 3.3 +/- 
0.5 Jy
(MJD 57818.4375). The source emission, peaking at RA=19:10:30, 
DEC=+07:52:00,
is compatible with the coordinates of the Galactic Bubble N82, including 
the
NIR Kanata source.

Within the half-power-beam-width from the source centroid, 7 radio sources
are present, mostly unidentified. We report below a list of the sources,
their coordinates, flux density, radius and possible association (source
SIMBAD):

NAME                R.A.        DEC         FLUX(Jy)    R(') ASSOC.
-------------------------------------------------------------------------
GPA 042.13-0.62  19:10:32.1  +07:53:22   2.81(@8.35GHz) 5      -
G042.114-0.622   19:10:31.7  +07:52:40   0.35(@1.4GHz)  - extragalactic
GB6 B1908+0747   19:10:28.8  +07:52:28   0.39(@327MHz)  <~3  HII?
HSNH 115         19:10:31.6  +07:52:18   2.1(@10GHz)    3.3    -
RFS 713          19:10:30.0  +07:51:51   3.3(@2.7GHz)   6      -
GP 1908+0746     19:10:33.7  +07:51:51   0.54(@327MHz)  6      -
RRF 312          19:10:21.3  +07:50:34   5.5(@1.4GHz)   13.3   -

Variability analysis on long and short time-scales are ongoing.

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), P. Giommi (ASI), C. Gronwall (PSU), H.A. Krimm
(CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien (GSFC/UMBC), 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) on behalf of the Swift 
team

and

Francesco Verrecchia (ASDC) and Marco Tavani (INAF / University of Rome
Tor Vergata) on behalf of the AGILE team report:


Swift-XRT has performed pointed observations of two sources within the
error region of the AGILE-GRID transient AGL J1914+1043 (Tavani et al.
LVC Circ. 20754): the IR transient reported by Yoshida et al (LVC Circ.
20784) and the Galactic microquasar GRS 1915+105, observing each field
for 1ks.

No X-ray source is detected at the location of the IR transient, with a
3-sigma upper limit of 9.7e-3 ct/sec. Assuming a power-law spectrum with 
Gamma=1.7 and NH=1.43e22 cm^-2 (the Galactic column along this line of 
sight; Willingale et al. 2013) this corresponds to an observed X-ray 
flux of 7.1e-13 erg cm^-2 s^-1.

GRS 1915+105 is a known X-ray emitter and is clearly detected in the XRT 
observations, with a mean count-rate of 87.8 (+1.63, -2.05) ct/sec,
which is ~20% lower than seen in Swift observations from 2016 November.

This circular is an official produce of the Swift and AGILE teams.

The LIGO Scientific Collaboration and Virgo report:

We have completed an initial Bayesian parameter estimation analysis of
the LIGO data around the time of the compact binary coalescence (CBC)
event candidate G275404 (GCN 20738
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 ) using LALInference (Veitch et al.,
PRD 91, 042003). This analysis used the IMRPhenomPv2 waveform
approximation, which includes the inspiral, merger, and ringdown
phases of the signal and accounts for the effects of spin precession.
We accounted for systematic errors due to uncertainty in the
calibration of the detectors' responses of up to 10% in amplitude and
10 degrees in phase. This follow-up analysis also used different, more
conservative assumptions on the detector noise properties.

The updated localization, LALInference.fits.gz, is available for
retrieval from the GraceDB event page:

https://gracedb.ligo.org/events/G275404 <https://gracedb.ligo.org/events/G275404>

The localization has arcs similar to the rapid BAYESTAR sky map, but
broader, and the conservative assumptions mentioned above result in
this case in a much larger area in the sky consistent with the
observed data. The 50% credible region spans 2000 deg2 and the 90%
credible region spans 17000 deg2 due to a diffuse component in the
probability distribution.

This parameter estimation analysis does not influence our estimation
of the significance of this event. It remains a marginal candidate
with a false alarm rate of about one in two months as reported in our
original Circular. If the signal is astrophysical, then the mass
estimates are consistent with a NSNS or NSBH binary.

V. Savchenko (ISDC, University of Geneva, CH)
on behalf of the INTEGRAL group:
C. Ferrigno ((ISDC, University of Geneva, CH),
S. Mereghetti (IASF-Milano, 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, Saclay/CEA, France)
A. Lutovinov (IKI, Russia) J.P. Roques (CESR, France)
R. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy)


INTEGRAL performed a target-of-opportunity (ToO) observation
containing the peak of the LIGO localization probability of G275404
(Sachdev et al 2017, GCN 20738
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 ) and its possible gamma-ray counterpart
AGL J1914+1043 (Tavani et al 2017, GCN 20754
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 ). In total 56% of the
LIGO probability and the whole probable localization region of AGL
J1914+1043 were observed in the field of view (FoV) of the INTEGRAL
instruments.

The observation containing the peak localization probability of
G275404 peak (RA= 299.1 Dec=49.3), started 81.5 hours after the
G275404 trigger time (2017-02-25 18:30:21.4 UTC , T0 hereafter) from
2017-03-01 04:09:58 UTC to 2017-03-02 05:45:58 UTC, corresponding to
an on-target time of 85.5 ks. We covered in total 40% of LIGO
localization probability with INTEGRAL/IBIS FoV. Every single
hour-long spacecraft pointing contained about 30% of the LIGO
localization probability.

The observation of AGL J1914+1043 started at T0+107.5 hours and
spanned from 2017-03-02 05:57:54 UTC to 2017-03-03 07:03:05 UTC, with
a total on-target time of 86.5 ks and including an extended region
within a distance of about 15 degrees from the target, securely
encompassing the region of probable localization reported by AGILE (4
deg 68% containment + 1 deg systematic error). This observation
includes 16% of G275404 localization in INTEGRAL/IBIS FoV and every
single hour-long instrument pointing contained about 13% of the LIGO
localization probability.

Additionally, by chance, INTEGRAL observed a non-negligible fraction
of the G275404 probability before the start of the dedicated
ToO. Despite limited coverage, these observations are useful, since
they were performed during the LIGO trigger and as well as immediately
before and after. The observation of the Galactic Bulge region from
2017-02-26T12:22:54 to 2017-02-26T16:03:52.396 collected 12.5ks of
data covering 1.5% of LIGO probability, complementary to that of the
ToO observation. The observation of the Norma Region between
2017-02-27T07:13:58.431 and 2017-02-28T01:48:14.473 collected 61ks of
data covering additionally 2% of the LIGO probability.

We investigated the data collected by INTEGRAL IBIS/ISGRI and
JEM-X. We did not find any new significant sources in the 90%
localization region of G275404.

In INTEGRAL/ISGRI observation of AGL J1914+1043 data between 25 and 80
keV we have found a weak excess with an SNR of 4.3 at RA=292.27
Dec=8.14 (radius of 5 arcmin, 90% containment), 4.6 deg from the
center of AGILE localization (RA=288.43 deg, DEC=10.72 deg, and error
radius R = 4 deg at 68% confidence + 1 deg systematic error).  We have
split the observation in two periods of equal duration, and found that
this excess is not detected with SNR more than 4 in any of them, hence
revealing no sign of evolution. If real, the excess would correspond
to a source with an average flux of 5.1+/-1.2 mCrab (5.1+-1.2e-11
erg/cm2/s) in the 25-80 keV band and 3.5+/-1.1 mCrab (2.9+-0.9e-11
erg/cm2/s) in 25-40 keV band. While this possible source is located in
a region frequently observed by INTEGRAL (for a total of 14Ms between
2003 and 2017), no possible detection was previously reported at its
position.

We estimate a probability of this excess happening randomly within the
5 degree radius of the AGILE localization to 3.5% or a significance of
2.1 sigma.

We derived an upper limit on the flux of a new source at the peak of
the LIGO localization probability of 6 mCrab (1.9e-10 erg/cm2/s) in
the 3-35 keV band, 3.6 mCrab (3.6e-11 erg/cm2/s) in the 25-80 keV
band, and 7 mCrab (8.2x10-11 erg/cm2/s) in the 80-200 keV band. The
upper limit depends on the source position in the field of view. About
40% of G275404 is observed with the sensitivity of down to 10 mCrab or
better.

The localization region of another LIGO event, G275697 (Siellez et al
2017, GCN 20763
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 ), was in the FoV of the INTEGRAL instruments, with the
30% of the LIGO localization observed by IBIS/ISGRI at any time from
the LIGO trigger time to 3.5 days after. At the moment of the LIGO
trigger as well as from -0.5 days to 0.3 days around it up to 8% of
the probability was in the ISGRI FoV, while at any other moment until
3.5 days after the trigger up to 15% of the probability was in the
FoV.

We note that omni-directional INTEGRAL/SPI-ACS observations around the
G275404 and G275697 triggers are reported in LIGO/Virgo Circulars
20755 and GCN 20768
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 .

N. Blagorodnova, K. De, R. Lunnan, M. Balokovic, N. Kamraj, M. Heida, D.
Stern and M. M. Kasliwal (Caltech)

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

On UT 2017-03-04, we spectroscopically classified the following iPTF
optical transient candidates (LVC GCN#20801
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 , LVC GCN#20790
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 ) using the
Double Beam Spectrograph (Oke & Gunn 1982) on the Palomar 200-inch Hale
Telescope. All spectra were reduced using the pyraf-dbsp pipeline (Bellm &
Sesar 2016). Classification were done with SNID (Blondin & Tonry, 2007) and
Superfit (Howell et al. 2005).

Name, Redshift, Classification, Notes
iPTF17bug, z=0.0167, Spectrum dominated by galaxy light (Consistent with
LVC GCN 20814
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 )
iPTF17bxk, z=0.077, SN IIn, Best match is 2005cl at +15d
iPTF17bpa, z=0.046, Spectrum dominated by host galaxy light, just outside
90% contour line (Consistent with LVC GCN 20814
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 )
iPTF17bpb, z=0.049, Spectrum dominated by host galaxy light
iPTF17bpc, z=0.039, Spectrum dominated by host galaxy light
iPTF17bsd, z=0.116, Spectrum dominated by host galaxy light
iPTF17bro, z=0.055, Spectrum dominated by host galaxy light
iPTF17bvo, z=0.0915, AGN?, double-peaked Balmer line

C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report on
behalf of

D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU),
D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan
(Warwick), P.Mazzali (LJMU),  C.Mundell (Bath), E.Pian (Pisa), D. Pollacco
(Warwick),  D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk
(Warwick), K.Wiersema (Leicester)

and the GROWTH (Global Relay of Observatories Watching Transients Happen)
collaboration.

---

We report the following Liverpool Telescope follow-up observations of EM
candidates originally reported in GCNs #20790
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  and #20801
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 . Observations were
made with the SPRAT spectrograph, and supernova classifications were
obtained using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).


iPTF17bug was observed on 2017-03-03 at 20:19UT. This is a nuclear source,
and the spectrum we obtain seems to be dominated by the host galaxy.

iPTF17bpa was observed on 2017-03-03 at 22:37UT. This source was reported
to be off-centre from it's host galaxy but we do not detect a transient
above the background galaxy emission in our acquisition image. The spectrum
seems to be galaxy dominated.

iPTF17bpt was observed on 2017-03-03 at 23:17UT. We classify this source as
a type Ia Supernova with z=0.074. A type Ib classification is also a
possibility. Note that this classification replaces the classification with
erroneously high z reported in GCN #20809
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 .

iPTF17bsi was observed on 2017-03-04 at 04:56UT. SNID classifies this
source as a Type II supernova (possibly IIP) at 2.7 days after peak with
z=0.028. This is significantly higher than the photometric z = 0.014 reported
for the host galaxy in GCN #20790
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 .

iPTF17btb was observed on 2017-03-04 at 05:29UT. We observe a bright point
source with a featureless spectrum - this is likely a dwarf nova in
outburst.

HAWC was operating and our real-time all-sky GRB monitoring analysis was running at the time of the G275404 event. At the time of the event, the HAWC detector was oriented at (��, ��) = (336.1��, 19.0��), local zenith. 33% of the LIGO/Virgo CWB probability contour fell within our observable field (0-45 deg zenith angle).

We continuously 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 contour on 3 timescales (1, 10, 100 sec) with a reduced threshold to account for the reduced number of trials. No significant candidates were identified.

Additionally, we searched for longer duration emission. Since the most probable region of the contour was setting at the time of the trigger, we observed this region during the following transit, 17-25 hrs after the GW event. We did not find a significant excess. HAWC has a 5-sigma point-source sensitivity to a flux >1 TeV of ~2x10^-11/cm^2/s, about ~1 "crab unit", for a single transit observation. 67% of the LIGO/Virgo contour is within HAWC's observable declination range.

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.

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

We observed 99 separate fields in two different regions of the G275404 bayestar skymap using our 0.43m robotic telescope at Teide Observatory, Tenerife, Spain. We acquired over 400 images across the first 6 nights of observations, all images were obtained using the R filter and 60s exposure length. Initial observations began at 2017-02-25T22:17:50, approximately 5 hours after the initial GCN alert was received. A detailed list of all the fields observed can be found on GraceDB under the EMObservations tab. Each FoV was 0.7x0.7 degrees centred around the given coordinates. Analysis is ongoing.



-- 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.

C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report on
behalf of

D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU),
D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan
(Warwick), P.Mazzali (LJMU),  C.Mundell (Bath), E.Pian (Pisa), D. Pollacco
(Warwick),  D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk
(Warwick), K.Wiersema (Leicester)

and the GROWTH (Global Relay of Observatories Watching Transients Happen)
collaboration.

---

We report the following Liverpool Telescope follow-up observations of EM
candidates originally reported in GCN #20790
Loading...
 
 . Observations were made with
the SPRAT spectrograph, and supernova classifications were obtained using
SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).


iPTF17bqh was observed on 2017-03-02 at 23:58UT. The spectrum is generally
featureless with some weak hints of Balmer lines in absorption, so we
believe this source to be a dwarf nova in outburst.

iPTF17bpt was observed on 2017-03-03 at 02:12UT. Based on a
weather-affected spectrum we classify this transient as a type Ia SN at +18
days with z=0.595.

R. Lunnan (Caltech), S. Papadogiannakis (OKC), N. Blagorodnova (Caltech),
A. A. Miller (Northwestern/Adler), L. P. Singer (NASA/GSFC), S. M. Adams
(Caltech), C. Cannella (Caltech), S. B. Cenko (NASA/GSFC), R. Walters
(Caltech), T. Barlow (Caltech), J. Rana (IUCAA), V. Bhalerao (IIT-B),  Y.
Cao (UW), R. Laher (IPAC), F. Masci (IPAC) and M.M. Kasliwal (Caltech)

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

We have continued tiled observations of LIGO/Virgo G275404 (LVC, GCN
20738
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 ) and LIGO/Virgo G275697 (LVC, GCN 20763
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 ) using the Palomar 48-inch
Oschin telescope (P48). Including our first night of observations on
2017-03-01 UTC (GCN 20791
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 ) and a second night on 2017-03-02, we have
observed a total of 256 fields spanning 1747 square degrees. We estimate a
20% chance that these fields contain the true location of G275404 and a
25% chance that they containing the true location of G275697.

During preliminary sifting through candidate variable sources using image
subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016)
pipelines, a total of 115 candidates were saved in the fields imaged.
Applying standard iPTF vetting procedures and removing transients with a
history of previous variability, we flagged 9 additional optical transient
candidates in the 90% localization contour of G275404, listed below, for
further follow-up.


iPTF17buf   98.583906       76.596292       05:24  19.59
pstar=0.962; nuclear/stellar?
iPTF17bug   97.67324        77.159053       05:24  18.6    0.0166  specz;
nuclear
iPTF17bur   295.1181        58.707877       11:38  19.14
pstar=0.016; nuclear/stellar?
iPTF17buu   114.100254      74.505262       05:33  19.92           Hostless
in iPTF reference but faint counterpart seen in PanSTARRS.
iPTF17buw   127.499818      73.935927       06:08  20.23
pstar=0.948; nuclear/stellar?
iPTF17bvo   133.140294      86.061384       06:11  19.55           nuclear;
pstar=0.042
iPTF17bvt   115.702547      74.553167       05:33  19.57
nuclear/stellar?; looks like three-star blend in PS1
iPTF17bwl   150.611516      8.822758        08:23  18.77   0.114   specz;
also detected 2017-03-01; nuclear; SDSS QSO
iPTF17bxk   149.643558      6.963137        08:23  19.99   0.077   specz;
offset 13.5" from the center of 2MASX J09583513+0657389

Two known transients detected by Pan-STARRS on 2017-02-16 also fall in this
localization region and were recovered with iPTF : PS17bjk (iPTF17bez) and
PS17bjd (iPTF17bfa).

Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on
2017-03-02. Magnitudes are based on image subtraction and in the Mould R
filter, calibrated with respect to point sources in SDSS as described in
Ofek et al. 2012.

We caution that many candidates are outside the SDSS footprint and lack a
secure star/galaxy classification for the underlying source. We flag these
as "nuclear/stellar?". Where available, we provide machine-learning
probability scores on whether the underlying source is a galaxy/star (0/1)
(Miller et al. 2016).

We encourage spectroscopic classification of these candidates, and
highlight iPTF17bug as a local candidate (d < 200 Mpc).

We are grateful to the Palomar crew (John Henning, Jeff Zolkower, Carolyn
Heffner, Jamey Eriksen, Nick Ganciu) for their hard work in reviving a
faulty declination encoder essential to collecting this dataset during the
last two days of iPTF survey operations.

David O. Cook (Caltech), Angela Van Sistine (UW Milwaukee), Leo Singer
(NASA/GSFC), and M. M. Kasliwal (Caltech)

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

We spatially cross-matched the LIGO/Virgo G275697 trigger (90% containment
volume; LVC GCN 20763
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 ) with our Census of the Local Universe (CLU; Cook et
al. in prep) galaxy catalog and found 7361 galaxies. This catalog is a
compilation of galaxies with existing redshifts from many sources (e.g.,
NED, SDSS, etc) and new galaxies from a 3PI four-filter narrow-band survey
to look for redshifted Halpha emission out to 200 Mpc with the Palomar
Oschin 48-inch telescope. Currently, the narrow-band survey is only
calibrated inside the footprint of SDSS. Of the 7361 galaxies in the error
volume, 6032 come from a compilation of known galaxies and 1329 are new,
emission-line CLU galaxy candidates.

We list here the top 20 galaxies sorted by star formation rate (SFR) and by
stellar mass (Mstar) for galaxies whose location on the sky and distance
falls in the 90% volume reported by the BAYESTAR probability sky map
(Singer et al. 2016), where the 90% credible volume measures 3.3e6 Mpc^3.
The sorted SFR list contains 2 new CLU galaxies with no previous
spectroscopic redshifts, and the sorted mass list contains 1 new CLU
galaxy. CLU J20203032+0734271 is an interacting triplet of galaxies, and
CLU J08550651+1944566 may be an interacting pair.


List of sorted SFRs:
          name             ra      dec    distMpc Log(sfr_fuv, Msun/yr)
Log(mstar, Msun)
----------------------- -------- -------- ------- ---------------------
----------------
              II Zw 096 314.3496  17.1273  148.35   2.486
10.78
2MASX J10315733-1846333 157.9887 -18.7761  172.43   1.922
11.14
  CLU J21083429+1804593 317.1430  18.0830  171.40   1.838
10.56
               MRK 0704 139.6084  16.3053  125.21   1.807
11.45
               MRK 1239 148.0796  -1.6121   85.34   1.756
11.63
         ESO 567- G 025 152.9059 -21.2538  128.15   1.733
11.04
2MASX J20104645+0107108 302.6935   1.1197  110.63   1.639
10.32
               NGC 2761 136.8779  18.4341  119.85   1.575
10.85
         MCG -05-26-006 161.8030 -28.9211  146.22   1.573
10.79
              UGC 11497 298.9081   2.1819  108.47   1.512
10.82
              UGC 05025 141.5137  12.7343  124.85   1.507
11.04
2MASX J12313717-4758019 187.9048 -47.9672  119.47   1.473
10.96
           CGCG 447-017 310.7770  21.6341  198.10   1.466
11.07
         ESO 267- G 029 183.4678 -47.2737   77.79   1.452
10.51
  CLU J08550651+1944566 133.7770  19.7489   52.82   1.447
8.56
2MASX J19512506+0432574 297.8542   4.5493  121.09   1.444
10.19
           TOLOLO 00013 167.3347 -30.3636  177.31   1.429
10.68
2MASX J11143157-2935412 168.6316 -29.5948  129.19   1.428
10.31
2MASX J20353916+0816162 308.9133   8.2711  114.50   1.403
10.67
                 VV 637 150.8623  -1.5467  197.44   1.390
10.69


List of sorted stellar masses:
          name             ra      dec    distMpc Log(sfr_fuv, Msun/yr)
Log(mstar, Msun)
----------------------- -------- -------- ------- ---------------------
----------------
               MRK 1239 148.0796  -1.6121   85.34   1.756
11.63
               MRK 0704 139.6084  16.3053  125.21   1.807
11.45
2MASX J10315733-1846333 157.9887 -18.7761  172.43   1.922
11.14
           CGCG 447-017 310.7770  21.6341  198.10   1.466
11.07
         MCG -03-26-030 152.8289 -17.2044  129.25   0.015
11.05
              UGC 05025 141.5137  12.7343  124.85   1.507
11.04
         ESO 567- G 025 152.9059 -21.2538  128.15   1.733
11.04
               NGC 2720 134.7836  11.1492  127.07  -0.271
11.04
              UGC 05025 141.5140  12.7344  123.28   1.496
11.03
2MASX J10260948-2034149 156.5394 -20.5708  175.36  -0.036
11.03
           CGCG 447-008 307.9770  18.4189  192.53  -0.068
11.03
2MASX J20235470+1341480 305.9779  13.6967  191.06   0.575
11.02
               NGC 2819 139.5387  16.1981  129.13  -0.277
11.00
         ESO 438- G 023 170.2215 -29.4031  127.39   0.430
10.99
2MASX J09493236-1406471 147.3848 -14.1132  179.73   0.209
10.99
2MASX J12313717-4758019 187.9048 -47.9672  119.47   1.473
10.96
              UGC 11602 309.4789  10.6313  110.68   0.355
10.95
  CLU J20203032+0734271 305.1260   7.5744  183.17   0.986
10.90
              UGC 05182 145.6040   4.2832  122.75  -0.222
10.90
2MASX J10370833-2242401 159.2847 -22.7112  158.88   0.763
10.89

The SFRs are derived from GALEX all sky kron FUV magnitudes via the
prescription of Murphy et al. (2011) and have been corrected for internal
dust extinction using a combination of GALEX FUV and 22um ALLWISE fluxes
(Hao et al. 2011). The quoted stellar masses are derived from 3.4um ALLWISE
fluxes and a mass-to-light ratio of 0.5 (McGaugh & Schombert et al. 2015).
AGN contributions to the SFRs and stellar masses are not corrected for.

M. M. Kasliwal (Caltech), S. M. Adams (Caltech), C. Cannella (Caltech), R.
Lunnan (Caltech), R. Ferretti (OKC), T. Kupfer (Caltech), L. P. Singer
(NASA/GSFC), S. B. Cenko (NASA/GSFC), R. Walters (Caltech), T. Barlow
(Caltech), J. Rana (IUCAA), V. Bhalerao (IIT-B), A. A. Miller
(Northwestern/Adler), Y. Cao (UW), R. Laher (IPAC), F. Masci (IPAC)

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 G275404 (LVC, GCN 20738
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 ) and
LIGO/Virgo G275697 (LVC, GCN 20763
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 ) using the Palomar 48-inch Oschin
telescope (P48) on the night of 2017-03-01 UTC (delay due to inclement
weather). We imaged 84 fields spanning 633 square degrees, with a 17%
chance of containing the true location of G275404. Of these, 47 fields (361
square degrees) were imaged twice, containing 11% of the probability of
containing G275404, and searched for transient candidates.

During preliminary sifting through candidate variable sources using image
subtraction by our IPAC (Masci et al. 2016) and NERSC (Cao et al. 2016)
pipelines, a total of 140 candidates were saved in the fields imaged.
Applying standard iPTF vetting procedures and removing transients with a
history of previous variability, we flagged 27 optical transient candidates
in the 90% localization contour of G275404, listed below, for further
follow-up.

Name         RA              Dec            UTC          R-mag      z
Notes
iPTF17bpa   150.966591      1.095135        09:07        18.72   0.0456
specz; off center from host
iPTF17bpb   154.902074      -2.992951       09:25        19.56   0.0511
photz; pstar=0.016; nuclear?
iPTF17bpc   155.671912      -3.647882       09:25        19.31
pstar=0.001; nuclear?
iPTF17bpd   155.181672      -4.163867       09:25        19.28
pstar=0.804; nuclear/stellar?
iPTF17bpk   157.626592      -11.121047      10:20        19.63
nuclear/stellar?
iPTF17bpm   161.324311      -14.376753      10:04        19.26
pstar=0.229; nuclear/stellar?
iPTF17bpn   161.238427      -14.017486      10:04        19.56
pstar=0.46; nuclear/stellar?
iPTF17bpo   158.494163      -12.65084       10:02        19.03
pstar=0.96; nuclear/stellar?
iPTF17bps   161.952768      -15.243493      10:04        19.76
hostless (very slow mover?)
iPTF17bpt   157.657157      -7.372908       09:29        19.49
fading (0.5 mag intra-night); pstar=0.89; nuclear/stellar?
iPTF17bpu   157.559861      -6.799173       09:29        19.81
pstar=0.612; nuclear/stellar?
iPTF17bpy   156.687516      -7.684226       09:29        19.98
pstar=0.933; nuclear/stellar?
iPTF17bqc   158.470076      -11.493302      10:02        19.62
pstar=0.717; nuclear/stellar?
iPTF17bqh   156.749276      -10.358467      10:00        19.49
rising (0.4 mag intra-night); nuclear/stellar?
iPTF17bqi   156.87908       -7.04181        09:29        19.41
pstar=0.962; nuclear/stellar?
iPTF17bqk   162.188261      -15.49746       10:04        19.76
nuclear/stellar?
iPTF17bqz   157.651689      -7.696641       09:29        19.83
pstar=0.885; nuclear/stellar?
iPTF17bro   288.344596      58.81211        10:59        19.82
rising (0.5 mag intra-night), nuclear?
iPTF17brp   291.671757      79.220007       11:47        19.42   0.076
photz; pstar=0.056; off center from host galaxy
iPTF17brr   289.432632      79.995864       11:47        19.88
pstar=0.898; nuclear/stellar?
iPTF17bru   294.594305      63.706556       11:36        19.95          off
center from host galaxy
iPTF17bsd   156.642225      -10.970993      10:00        19.68
rising (0.3 mag intra-night); nuclear
iPTF17bsi   297.077103      78.352918       12:01        19.08   0.014
photz; off center from host galaxy
iPTF17bst   156.998904      -7.216924       09:29        19.87
pstar=0.973; nuclear/stellar?
iPTF17btb   302.938179      72.930472       12:03        18.56
nuclear/stellar?
iPTF17btc   309.740925      72.580678       12:03        18.97
nuclear/stellar?
iPTF17bth   307.33055       68.241724       12:05        19.31
nuclear/stellar?

Positions are stated in the ICRS. Discovery times are noted in UTC hh:mm on
2017-03-01. Magnitudes are based on image subtraction and in the Mould R
filter, calibrated with respect to point sources in SDSS as described in
Ofek et al. 2012.

We caution that many candidates are outside the SDSS footprint and lack a
secure star/galaxy classification for the underlying source. We flag these
as "nuclear/stellar?". Where available, we provide machine-learning
probability scores on whether the underlying source is a galaxy/star (0/1)
(Miller et al. 2016).

We encourage spectroscopic classification of these candidates. In
particular, we highlight iPTF17bpt, iPTF17bqh, iPTF17bsd as fast-evolving
by more than 0.3 mag in the same night; iPTF17bpa and iPTF17bsi as local
transients (d < 200 Mpc), and iPTF17bpa and iPTF17btb as bright transients
(m < 19 mag).

We are grateful to the Palomar crew (especially John Henning, Jeff
Zolkower, Carolyn Heffner, Jamey Eriksen, Nick Ganciu) for their hard work
in reviving a faulty declination encoder essential to collecting this
dataset during the last two days of iPTF survey operations.

Adam Goldstein (USRA) and Colleen Wilson-Hodge (NASA/MSFC) report on behalf
of the GBM-LIGO Group:
Lindy Blackburn (CfA), Michael S. Briggs (UAH), Jacob Broida (Carleton
College), Eric Burns (UAH), Jordan Camp (NASA/GSFC), Tito Dal Canton
(NASA/GSFC), Nelson Christensen (Carleton College), Valerie Connaughton
(USRA), 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)

Fermi GBM observed 77% of the LALInference sky map at the time of the LIGO
trigger, and we set the following flux upper limits for the entire visible
sky map (excluded region is a circle with radius of 68 degrees centered on
RA, Dec = 134.5, +25.6).

Using a hard Band function with (Epeak, alpha, beta) = (500 keV, -0.5,
-2.5), we set a 3 sigma, 1-second-averaged flux upper limit for any
transient within 30 s of the LIGO trigger time in the 10-1000 keV band
ranging from 5.0e-7 to 1.4e-6 erg/s-cm^2.  Using an exponentially cutoff
power law parametrized with (Epeak, index) = (566 keV, -0.42), which
represents the average GBM-triggered short GRB, the upper limit ranges from
5.4e-7 to 1.4e-6 erg/s-cm^2.  The upper limit in the region of the
AGILE-GRID candidate, AGL J1914+1043 (Tavani et al., GCN 20754
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 ), is 5.0e-7
erg/s-cm^2 using the hard Band function and 5.4e-7 erg/s-cm^2 using the
cutoff power law.

Using the Earth Occultation technique (Wilson-Hodge et al. 2012, ApJS, 201,
33) to estimate the amount of persistent emission during a 48-hour period
centered on the LIGO trigger time, we place the following range of 3-sigma
day-averaged flux upper limits based on observed sources over the entire
LIGO sky map:

Energy       min  max  median
--------------------------------
 12- 27 keV: 0.08 0.62 0.12 Crab
 27- 50 keV: 0.14 0.87 0.21 Crab
 50-100 keV: 0.20 1.27 0.29 Crab
100-300 keV: 0.39 2.72 0.57 Crab
300-500 keV: 3.75 28.1 5.58 Crab

These limits are based on the minimum requirement that each source in the
Earth Occultation catalog was Earth-occulted at least 6 times in each of
the 24 hour periods preceding and following the LIGO trigger and that the
occultations were well separated from nearby bright sources.

Yoshida, M., Utsumi, Y., Nakaoka, T., Abe, T., Nagashima, H.,
Kawabata, K. S., Kawabata, M., Shiki, K. (Hiroshima U.),
Ohsawa, R. and Sako, S. (U. of Tokyo) on behalf of J-GEM
collaboration

We performed near-infared H-band observations of nearby galaxies
in the error circle of the gamma-ray transient candidate found
in the AGILE-GRID data, AGL J1914+1043 (Tavani et al. GCN 20754
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 ),
which is located at the edge of the skymap of G275404 (GCN 20738
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 )
with 1.5m Kanata telescope on UT 2017-02-27. The instrument used
was an optical near-infrared simultaneous camera HONIR.

We found a bright near-infrared transient in the observed field of
GL191032+075314. The data was taken at 20:32UT on 2017-02-27. The
H-band AB magnitude of the source was 16.3 +- 0.02. The location
of the source is

     RA=19:10:31.46, DEC=+07:53:52.0 .

We also conducted an I-band observation for this area simultaneously.
No transient source was detected with the 5-sigma I-band limiting
magnitude of 19.6. There is no bright counterpart in 2MASS H-band
data, but a point source (SSTGLMC G042.1312-00.6118; in GLIMPSE I
Spring '07 Catalog) is clearly seen at the same position in 3.6 um
data taken by Spitzer GLIMPSE survey.

The observation log with 5-sigma limiting magnitudes is shown
below.


Telescope: Kanata 1.5m telescope
------------------------------------------------------
galaxy          RA       DEC     UT              H
------------------------------------------------------
GL191032+075314 287.6351 7.8871  2017/2/27-20:32 18.7
GL192215+140356 290.561  14.0655 2017/2/27-21:11 17.5
GL191327+105427 288.3622 10.9076 2017/2/27-20:52 18.5
GL191032+075314 287.6351 7.8871  2017/2/27-20:32 18.3
GL190530+100857 286.3748 10.1491 2017/2/27-20:12 18.1
GL190618+125620 286.5759 12.9388 2017/2/27-19:53 18.2
GL190415+125637 286.0637 12.9437 2017/2/27-19:33 17.8
GL185836+113738 284.6512 11.6271 2017/2/27-19:13 17.9
------------------------------------------------------

Yoshida, M., Utsumi, Y. (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 G275404 (LVC; GCN 20738
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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) at OAO in the framework of J-GEM collaboration. We obtained
optical three color data, g', Rc, and Ic, with MITSuME. Near-infrared
J-band data were obtained with OAOWFC.

The 5-sigma limiting AB magnitudes are listed below.
No optical/infrared transient source corresponding to the GW event
was found by these observations.


Telescope: Akeno-MITSuME
---------------------------------------------------------------
galaxy          RA       DEC     UT              g'   Rc   Ic
---------------------------------------------------------------
GL070934+815806 107.392  81.9682 2017/2/26-10:57 17.2 16.3 16.2
GL082903+631748 127.2626 63.2968 2017/2/26-13:01 18.5 17.8 17.1
GL080157+755626 120.4879 75.9405 2017/2/26-12:32 17.5 16.7 16.4
GL205542+694433 313.9234 69.7426 2017/2/26-09:55 16.3 15.1 14.7
---------------------------------------------------------------

Telescope: OAO-MITSuME
---------------------------------------------------------------
galaxy          RA       DEC     UT              g'   Rc   Ic
---------------------------------------------------------------
GL080414+625854 121.0578 62.9817 2017/2/26-12:29 19.2 19.0 18.7
GL073200+834257 113      83.7157 2017/2/26-16:24 18.7 18.8 18.2
GL073048+734223 112.702  73.7063 2017/2/26-16:04 19.1 18.7 17.7
GL080012+681439 120.0508 68.2442 2017/2/26-15:04 19.1 18.9 18.6
GL080925+675304 122.3541 67.8845 2017/2/26-14:44 19.1 18.9 18.5
GL081102+674602 122.7601 67.7671 2017/2/26-14:24 19.2 19.1 18.7
GL101338-005532 153.4096 -0.9255 2017/2/26-14:01 18.3 18.4 17.8
GL080408+625902 121.0333 62.9839 2017/2/26-12:29 19.2 19.0 18.7
GL072924+720740 112.3508 72.1279 2017/2/26-12:08 18.5 18.4 18.1
GL072301+770105 110.7546 77.018  2017/2/27-16:34 19.6 19.1 18.2
GL081343+642011 123.4296 64.3365 2017/2/27-16:14 19.6 19.3 18.8
GL082406+672912 126.023  67.4866 2017/2/27-15:55 19.4 19.3 18.7
GL042619+861143 66.5777  86.1953 2017/2/27-15:11 19.3 19.1 18.5
GL053258+834643 83.2431  83.7786 2017/2/27-14:51 19.2 19.2 18.7
GL054237+832440 85.6532  83.411  2017/2/27-14:31 19.2 19.3 18.7
GL064623+750738 101.5974 75.1273 2017/2/27-14:12 19.4 19.2 18.7
---------------------------------------------------------------

Telescooe: OAOWFC
------------------------------------------------------
galaxy          RA       DEC     UT              J
------------------------------------------------------
GL072256+782247 110.7315 78.3796 2017/2/27-15:46 18.8
GL081343+642011 123.4296 64.3365 2017/2/27-15:20 18.0
GL072301+770105 110.7546 77.018  2017/2/27-14:54 18.8
GL080925+675304 122.3541 67.8845 2017/2/27-14:08 18.8
GL081102+674602 122.7601 67.7671 2017/2/27-14:08 18.8
GL080414+625854 121.0578 62.9817 2017/2/27-13:23 18.9
GL064623+750738 101.5974 75.1273 2017/2/27-12:37 18.8
GL080925+675304 122.3541 67.8845 2017/2/27-11:51 18.7
GL081102+674602 122.7601 67.7671 2017/2/27-11:51 18.7
------------------------------------------------------

David O. Cook (Caltech), Angela Van Sistine (UW Milwaukee) and M. M.
Kasliwal (Caltech)

report on behalf of the iPTF and GROWTH collaborations

We spatially cross-matched the LIGO/Virgo G275404 trigger (90% containment;
LVC GCN 20738
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 ) with our Census of the Local Universe (CLU; Cook et al. in
prep) galaxy catalog and found 8700 galaxies. This catalog is a compilation
of galaxies with existing spectroscopic redshifts from many sources (e.g.,
NED, SDSS, etc) and new galaxies from a 3PI four-filter narrow-band survey
to look for redshifted Halpha emission out to 200 Mpc with the Palomar
48-inch telescope. Currently, the narrow-band survey is only calibrated
inside the footprint of SDSS. Of the 8700 galaxies in the error region,
7792 come from a compilation of known galaxies and 908 are new,
emission-line galaxy candidates.

We list here the top 20 galaxies sorted by star formation rate (SFR)
independent of distance. These SFRs are derived from GALEX all sky kron FUV
magnitudes via the prescription of Murphy et al. (2011) and have been
corrected for internal dust extinction using a combination of GALEX FUV and
22um ALLWISE fluxes (Hao et al. 2011). The quoted stellar masses are
derived from 3.4um ALLWISE fluxes and a mass-to-light ratio of 0.5 (McGaugh
& Schombert et al. 2015).

Name, RA (J2000), DEC (J2000), Distance (Mpc), log(SFR_FUV in Msun/yr),
log(Mstar in Msun)
------------------------------------------------------------
------------------------------
PGC45371, 196.60885, -40.41467, 64.3, 1.56, 11.41
PGC34266, 168.67487, -23.72769, 50.0, 1.50, 10.56
PGC27353, 144.20834, 11.75102, 123.1, 1.45, 10.58
VV 637,   150.86235, -1.54665, 197.5, 1.40, 10.69
UGC 05304 NED02, 148.293, 7.87353, 174.3, 1.33, 10.37
SDSS J094914.91+132616.9, 147.312, 13.438, 173.9, 1.33, 9.99
PGC62504, 282.907292, 23.6348261, 62.5, 1.32, 10.38
PGC45247, 196.28554, -32.19128, 135.4, 1.32, 10.90
PGC35241, 171.84762, -29.25758, 102.3, 1.30, 10.65
PGC28191, 147.17049, 9.00879, 127.9, 1.29, 10.69
MCG-01-27-027, 159.14729, -7.11283, 117.3, 1.28, 10.76
PGC63696, 297.24833, 50.3130183, 106.5, 1.27, 10.91
PGC29225, 151.15092, -1.74539, 195.5, 1.27, 10.57
PGC28271, 147.46491, 10.43199, 126.4, 1.27, 10.53
PGC30127, 154.7378, 1.66004, 196.6, 1.25, 10.71
PGC1195530, 151.70616, 1.4573, 198.7, 1.25, 10.64
PGC2672630, 300.72775, 64.89389, 189.4, 1.18, 10.93
PGC82908, 155.9038, -4.85393, 166.6, 1.16, 10.79
PGC28240, 147.34549, 1.14542, 107.1, 1.15, 10.86
CLU J20115561+6028326, 302.981, 60.4759, 176(+/-30), 1.13, 10.64

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 G275404 (LVC, GCN
20738
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 ) using the 1-m Chinese Near Earth Object Survey Telescope (CNEOST)
at Xuyi, Jiangsu, China.

CNEOST has a FOV of 3.0x3.0 deg^2, and carried out observations during
10:44:55.9 - 14:44:22.4 UT and 19:46:14.6 - 21:47:47.6 UT on 2017-02-26
in the Sloan r-filter. The skymap coverage is at

https://dl.dropboxusercontent.com/u/3665676/G275404/skymap20170226NEOST.pdf

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

Preliminary analysis doesn't reveal optical transient brighter than
m(r)~17.5 mag that is positionally coincident with SDSS host galaxy
whose spectroscopic or photometric redshifts is < 0.1.

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

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

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

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

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

MASTER OT J192402.43+421720.0 - bright PSN in PGC2195963

  MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic
Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec)
= 19h 24m 02.43s +42d 17m 20.0s on 2017-02-27 03:59:05.256UT during 
LIGO G275404 inspection (2017-02-25 18:30:51 UTC event time).

The OT unfiltered magnitude is ~16.6m (mlim=18.4).
The OT is seen in 5 image. There is no minor planet at this place.

There is PGC2195963 disc galaxy in 12.3" of this PSN ( http://leda.univ-lyon1.fr/ledacat.cgi?o=PGC2195963 )

We have reference image on 2016-03-19 05:07:19UT with unfiltered  mlim=19.8.
Spectral observations are required.

The discovery and reference images are
http://master.sai.msu.ru/static/OT/MASTEROTJ192402.43+421720.0.png



The position of  MASTER OT J173532.70+103810.5 (Lipunov et al. GCN #20740
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 , 
Sollerman et al. GRC #20758) is inside G274296 (2017-02-17) LIGO 
localization (Shawhan et al. GCN #20689
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  )

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 G275404 trigger time, UT 2017-02-25 18:30:21.374, 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 baystar skymap provided by LVC (baystar.fits.gz), the sky visible to CZTI has 22.1% 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 parameters, with alpha = -1, beta = -2.5 and E_peak = 300 keV. The sensitivity of CZTI varies with direction. We weight the sensitivity by the baystar 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 1.6e-07 ergs/cm^2, 3.9e-07 ergs/cm^2 and 9.0e-07 ergs/cm^2 for search timescales of 0.1, 1, and 10 seconds respectively. The corresponding flux upper limits for the three timescales are 1.6e-06, 3.9e-07, and 9.0e-08 ergs/cm^2/sec respectively.

Plots showing CZTI sensitivity as a function of direction for this event can be found at https://gracedb.ligo.org/apiweb/events/G275404/files/G275404_CZTI_limits.pdf,0

N. Blagorodnova (Caltech), A. Ho (Caltech), T. Hung (UMd), K. Vyhmeister
(Caltech), S. R. Kulkarni (Caltech), D. Cook (Caltech), A. van Sistine (UW
Milwaukee) and M. M. Kasliwal (Caltech)

report on behalf of the iPTF and GROWTH collaborations

We observed the transient MASTER PSN reported in LVC GCN #20759
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 , using LRIS
on the Keck I Telescope, on 2017-02-26 at 05:45 UT. The spectrum shows
relatively broad features at z=0.017. A SNID fit is consistent with a Type
Ic (possibly Ic broad-line) a month after maximum light. The host galaxy,
which does not have a previously known spectroscopic redshift, is also a
line emitter in the CLU (Census of the Local Universe; Cook et al. 2017)
narrow-band redshifted Halpha imaging, consistent with being local.

A. Melandri, P. D'Avanzo (INAF-OAB), G. Greco (Urbino University/INFN Firenze), D. Fugazza, S. Covino, (INAF-OAB), E. Palazzi (INAF-IASF 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), 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 (GRAWITA) report:

We carried out optical/NIR follow-up observations of the LIGO/Virgo GW trigger G275404 (LVC GCN Circ. 20738
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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 26 from 00:15:16 UT to 04:52:42 UT (from 5.75 to 10.37 hours after T0, LVC GCN Circ. 20738
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 ), simultaneously in the g, r, i, z and H bands. 

We observed the twenty brightest (according to the B magnitude reported in the GLADE catalogue) galaxies within the bayestar probability sky map visible from La Silla. The galaxies with a catalogued distance in the range 200-360 Mpc (evaluated on the basis of directional distance information, Singer et al. 2016, ApJL 829, 15) and brighter than Mag(B)=15.4 were selected within the 60% containment  probability contour of the sky map using the GWsky script (https://github.com/ggreco77/GWsky).


RA(J2000)  Dec(J2000) Dist(Mpc) Mag(B)
---------------------------------------
166.78835  -18.02376  309.030   14.37
169.72995  -20.43487  275.423   14.83
160.82343  -12.36031  235.505   14.97
164.62923  -15.38000  292.415   15.04
159.06644  -12.72557  229.087   15.07
157.75930  -10.56777  276.694   15.13
165.18204  -19.41204  255.859   15.18
182.20964  -31.44722  204.174   15.21
159.31235  -11.35495  231.560   15.23
168.87087  -20.79923  279.087   15.26
169.93326  -21.97061  354.813   15.29
174.77983  -27.54560  275.423   15.31
160.25761  -11.44282  235.303   15.31
166.36340  -21.09875  280.543   15.35
160.15845  -14.25566  231.206   15.37
166.13525  -18.84047  292.415   15.38
172.93570  -25.07778  280.543   15.38 
156.54243  -07.94825  285.508   15.38
173.67679  -24.94764  221.690   15.39
169.13541  -20.90190  297.852   15.40

A preliminary analysis reveals no obvious optical/NIR candidate counterpart in the above galaxies down to the following magnitudes: r > 19.5, H > 17.0 (AB, 3sigma upper limit, calibrated against the APASS and 2MASS catalogues, respectively).
 
Further analysis is in progress.

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

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

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

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

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

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

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

MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) 
= 19h 50m 04.70s +52d 38m 56.2s on 2017-02-26.26975 UT during inspection 
of G275404.

The OT unfiltered magnitude is ~ 19.0m (m_limit=19.5m).

This PSN is in 2.4W,2.6N of disc galaxy PGC2420186 
(http://leda.univ-lyon1.fr/ledacat.cgi?PGC2420186 )

This PSN is seen in 3 images. There is no minor planet at this place.

We have reference image without OT on 2016-05-07.15047 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/195004.84523853.6.png

Spectral 
observations are required.

J. Sollerman (OKC), S. Smartt (QUB) and M. M. Kasliwal (Caltech)

report

The position of  MASTER OT J173532.70+103810.5 (LVC GCN #20740
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 ) is outside
the LIGO 90% localization contour. Further follow-up of the possibly fast
fading nature of the source may not be necessary in the GW context.

J. Cooke, I. Andreoni, U. Mestric (Swinburne Univ.), T. Moriya (NAOJ)

 

A spectrum of the MASTER transient OT J105958.00-115756.5 (GCN Circ. 20748
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 ) was taken with the Keck telescope on 2017-02-26.54 UT during the follow up of the LIGO event G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738
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 ).

 

The observations were performed with the Low Resolution Imaging Spectrometer for a total exposure time of 2300s under several magnitudes of variable cloud extinction.



The preliminary analysis reveals a blue and mostly featureless spectrum at redshift z=0.0017. The spectrum shows evidence of Balmer series lines in absorption, with a potential weak emission in the H-gamma trough.  

 

This result is not inconsistent with Lipunov et al. (GCN Circ. 20748
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 ), who suggest the event to be a CV.

D. Kocevski (NASA/MSFC), N. Omodei (Stanford), G. Vianello (Stanford), J. L. Racusin (NASA/GSFC), 
S. Buson (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 
G275404.

Fermi-LAT had an instantaneous coverage of ~10% at the time of the trigger (T0 =  2017-02-25 
18:30:21.374 UTC), and reached 100% cumulative coverage within ~8 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 map in the 
time window from T0  to T0 + 10 ks, and no significant new sources are found. 

We also performed a search which adapted the time interval of the analysis to the exposure of each 
region of the sky. No significant candidate counterpart was found. 

The position of the AGILE candidate counterpart (Tavani et al., GCN 20754
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 ) was outside of the LAT 
field of view at the time of the LIGO event until T0+3.5 ks.  Searching over an interval from T0+3.5 to 
T0+6.7 ks, we do not find any significant excess at the AGILE position, placing an upper limit in the 
100 MeV - 100 GeV band of 3e-10 erg/cm2/s.

Using LAT Low Energy (LLE) data (Pelassa et al 2010), we perform a counting analysis at energies 
>30 MeV.  LLE is a loose event selection allowing for larger incident angles and lower energies with
respect the standard LAT likelihood analysis.  We searched for excesses coincident with the AGILE 
candidate at the time of the LIGO trigger, 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.

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 G275404.  The satellite was
pointing at RA=17:44:43 Dec=-25:57:27 (in the direction of the
Galactic Center region), 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.

The INTEGRAL Burst Alert System (IBAS) did not identify any unusual
transients in coincidence with the LIGO/Virgo trigger. The IBAS
inspects both ISGRI Field of View and all-sky SPI-ACS light curve.

The IBAS trigger closest in time to the GW candidate ("Weak" ISGRI
trigger 7706) happened at UTC 2017-02-25 11:32:15.56 and it's location
(RA=270.48, Dec=-25.08, 3.73 arcmin radius 68% containment,
statistical uncertainty only) was outside the 90% probability
containment of the LIGO localization region.

The nearest excess over the background rate identified by SPI-ACS
offline pipeline happened 453 seconds after the LIGO/Virgo trigger. It
has an SNR of 5.5, duration of 100 ms, and is compatible with cosmic
ray origin.

We investigated the SPI-ACS, IBIS/Veto, and IBIS/ISGRI light curves
between -500 and +500 s from the trigger time (2017-02-25 18:30:21.3
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 4.3e-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 1.5e-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 30% 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.

M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Giuliani
(INAF/IASF-Mi), A. Bulgarelli (INAF/IASF-Bo), F. Verrecchia (ASDC and
INAF/OAR), P. Munar-Adrover, M. Cardillo (INAF/IAPS),  V. Fioretti, A.
Zoli , N. Parmiggiani (INAF/IASF-Bo), M. Pilia (INAF/OA-Cagliari),  C.
Pittori (ASDC and INAF/OAR), I. Donnarumma, G. Piano (INAF/IAPS), F.
Lucarelli (ASDC and INAF/OAR), 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,
G. Minervini (INAF/IAPS), A. Trois (INAF/OA-Cagliari), report on behalf
of the AGILE Team:

Following up on the analysis of AGILE-GRID data in response to the LIGO/Virgo
GW event G275404, we performed an improved search for transient gamma-ray
emission within the G275404 localization region.

The AGILE-GRID had significant exposure of a good fraction of the G275404
localization region before and after the LIGO trigger time
(T0=2017-02-2518:30:21.374 UT).
Additional analysis in the energy range 30 MeV-50 GeV reveals the existence
of a 3.6-sigma gamma-ray transient event during the interval - 20 / + 10 sec
from T0, at the position with centroid coordinates: R.A.= 288.43 deg,
DEC= 10.72 deg (Galactic l = 45.0, b = 0.0), and error radius R = 4 deg
(stat. 68% confidence) + 1 deg (syst.). We name this transient AGL J1914+1043.

Despite its weakness, we consider AGL J1914+1043 an interesting source
candidate for its timing properties and position within the G275404
localization region.

No MCAL trigger event was recorded on board in coincidence with AGL
J1914+1043 which appears to be detected only at energies above 70 MeV.

This measurement was obtained with AGILE observing a large portion of the
sky in spinning mode. Additional analysis of AGILE data is in progress.
Multifrequency observations of the AGL J1914+1043 field are encouraged.

C. Fremling (OKC), F. Taddia (OKC), R. Amanullah (OKC), J. Sollerman (OKC),
M. M. Kasliwal (Caltech)

report on behalf of the iPTF and GROWTH collaborations

We observed the transient MASTER OT J173532.70+103810.5 reported in LVC GCN
#20740
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 , using ALFOSC on the Nordic Optical Telescope, on 2017-02-26 at
05:40 UT.

We do not detect any transient at the reported coordinates, in agreement
with observations from the Liverpool Telescope (LVC GCN # 20750). The
3-sigma limiting (unfiltered) magnitude of our stacked acquisition frames
at the expected position of the transient is  ~21.1 mag.

This would imply an extremely fast rate of fading > approx. 10 mag / day!
We caution that there is a variable star (PTF1717w) which is within a few
arcsec of the reported MASTER OT position. But this nearby variable star
only shows variations between roughly 19.0-19.6 mag in R-band in archival
PTF data. Additional follow-up is encouraged.

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), 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 83 observations of galaxies (from the
2MPZ catalogue) within the LVC error region for the GW trigger G275404,
using the 'bayestar' GW localisation map. As this is a 3D skymap,
galaxy distances were taken into account in selecting which ones to
observe. The observations currently span from 17 ks to 42 ks after the
LVC trigger, and cover 9.9 sq degrees on the sky (corrected for
overlaps). This covers 0.014 of the probability in the LVC skymap, and
0.028 of the probability in the LVC map after convolving with the 2MPZ
galaxy catalogue, as described by Evans et al., (2016, MNRAS,  462,
1591).

No new X-ray sources have been detected.

This circular is an official product of the Swift team.

M. Ageron (CPPM/CNRS), B. Baret (APC/CNRS), A. Coleiro (IFIC & APC), 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 G275404 event using the initial LIGO skyprobcc_cWB probability map at event time (LVC GCN Circ. 20738
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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/G275404.png (gwantares/ANT@GW). Considering the location probability provided by the LIGO collaboration, there is a 45% chance that the GW emitter was in the ANTARES field of view.

No up-going muon neutrino candidate events were recorded within the 90% contour during a +/- 500s time-window centered on the G275404 event time. The expected number of atmospheric background events in the region visible by ANTARES is ~1.3e-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.

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.

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

We attempted to observe the transient MASTER OT J173532.70+103810.5
reported in GCN #20740
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 , using the SPRAT spectrograph on the Liverpool
Telescope, on 2017-02-26 at 05:19 UT.

We do not detect a transient at the reported coordinates. We estimate the
limiting (unfiltered) magnitude of our acquisition frame to be ~19.5.

V.M.  Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Shumkov,
  P.Balanutsa, V.G. O.Gress, Kornilov, A.Kuznetsov, 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


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

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

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

MASTER OT J105958.00-115756.5 - possble new CV ?

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )
  discovered OT source at (RA, Dec) = 10h 59m 58.00s -11d 57m 56.5s on 
2017-02-25.96032 UT during LIGO/Virgo G275404 (GCN 20738
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 ).

The OT unfiltered magnitude is 17.1m (mlim = 20.0).

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

We have reference image on 2015-05-17.82159 UT with  unfiltered mlim= 
20.0m.
There is GALEX-DR5 source in half pixel offset.

Spectral observations are required.

T. Sakamoto (AGU), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),
D.M. Palmer (LANL), 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 G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738
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 ),
where T0 is the LIGO trigger time (2017-02-25T18:30:21.374023 UTC).

The BAT pointing position at T0 is
    RA   = 174.752 deg,
    DEC  = -37.723 deg,
    ROLL = 153.273 deg.
The BAT Field of View (>0.1 partial coding) covers 18.68% of the integrated
LIGO localization probability.

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 ~ 7.3 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 81.32% 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.

J.Y. Wei (NAOC), X.H. Han (NAOC), X.M. Meng (NAOC), N. Leroy (LAL),
 S. Antier (LAL), C. WU (NAOC), L.P. Xin (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. G?tz (CEA), C.Lachaud (APC),
on behalf of the SVOM Gravitational Astronomy group report:

We observed about 3200 square degree (8 sky regions) of the skymap
of the advanced LIGO trigger G275404, 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 46.6% prior
probability that these 8 regions contain the true location of the
source.

The coordinates of the 8 regions and observation time are list following:

start-obs(UTC)  end-obs(UTC)    Ra      Dec     Camera_ID
2017-02-25      19:23:51.9      2017-02-25      20:41:04.7      10:33:59.6
     +30:12:22                       C3
2017-02-25      19:23:51.9      2017-02-25      20:41:06.2      10:38:05.6
     +10:07:57                       C4
2017-02-25      19:23:42.2      2017-02-25      22:13:19.6      17:18:04.0
     +69:28:00                       C5
2017-02-25      19:23:44.7      2017-02-25      22:13:38.0      17:21:47.1
     +50:28:32                       C6
2017-02-25      13:01:04.2      2017-02-25      21:37:38.1      09:21:25.5
     +69:40:01                       C7
2017-02-25      13:01:04.2      2017-02-25      21:37:39.7      09:23:01.6
     +50:00:25                       C8
2017-02-25      21:39:38.3      2017-02-25      22:13:28.5      20:00:36.6
     +69:38:42                       C7
2017-02-25      21:39:38.3      2017-02-25      22:13:25.5      20:01:12.7
     +50:00:21                       C8

The first image (which is covered in our routine survey) was taken
 ~5 hours 29 minutes before the event trigger. No any significant
transient is found in our online pipeline. The image analysis is
ongoing in detailed processing with our offline pipeline.

M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), P. Munar-Adrover, M. Cardillo (INAF/IAPS), F. Verrecchia (ASDC
and INAF/OAR), A. Bulgarelli, V. Fioretti, A. Zoli , N. Parmiggiani
(INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), I. Donnarumma, G. Piano
(INAF/IAPS), F.Lucarelli (ASDC and INAF/OAR), A. Giuliani (INAF/IASF-Mi),
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, G. Minervini (INAF/IAPS), A.
Trois (INAF/OA-Cagliari), report on behalf of the AGILE Team:

In response to the LIGO/Virgo GW trigger G275404 we performed an analysis
of the AGILE Gamma-Ray Imaging Detector (GRID) data on different
timescales. On LIGO trigger time (T0=2017-02-25 18:30:21.374 UT) the GRID
exposure covered about 30% of the LIGO localization region (in the time
interval T0-100s, T0+100s) that was observed with off-axis angles between
10 and 70 deg.

An analysis of the data in the energy range 50 MeV - 10 GeV was performed
on timescales from 2 to 100 sec centered at T0. Preliminary values of
3-sigma upper limits obtained within the accessible G275404 localization
region are reported below:

1.8e-06 erg cm^-2 s^-1 for integration time of 2s,

1.5e-07 erg cm^-2 s^-1 for integration time of 20s,

3.5e-08 erg cm^-2 s^-1 for integration time of 100s.

These ULs apply to a large fraction of the GRID-exposed LIGO localization
region. We are currently analyzing the significance of a gamma-ray source
candidate within that region.
These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.

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
(USRA), 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 81% of the LIGO probability map for G275404 at the
event time, with much of the northern high probability region and half of
the southern arc observed. There is no GBM
on-board trigger around the event time. The untargeted ground-based
search of GBM data for short-duration GRBs (Briggs et al., in prep) found
no candidates close in time to G275404.
The targeted search of the GBM data ([1], [2]) also did not find a
significant gamma-ray signal. This search processes time scales of 0.256 to
8.192 s within 30 s of the LIGO event. No interesting gamma-ray candidate
was found within this time window.

Any prompt gamma-ray burst emission, above the GBM detection threshold,
must have been occulted by the Earth for Fermi.  The Earth-occulted region
is a circle with radius of 68 degrees, centered on RA, Dec = 134.5, +25.6.

Further analysis and upper limits will be reported later.

[1] L. Blackburn et al. 2015, ApjS 217, 8
[2] A. Goldstein et al. arXiv:1612.02395
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A. Ursi (INAF/IAPS), M. Pilia (INAF/OA-Cagliari), M. Tavani (INAF/IAPS,
and Univ. Roma Tor Vergata), A. Bulgarelli, V. Fioretti, N. Parmiggiani
(INAF/IASF-Bo), P. Munar-Adrover (INAF/IAPS), F. Verrecchia (ASDC and  
INAF/OAR),
A. Zoli (INAF/IASF-Bo), C. Pittori, F. Lucarelli (ASDC and INAF/OAR),
G. Piano, A. Argan (INAF/IAPS), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS),
Y. Evangelista, I. Donnarumma (INAF/IAPS), G. Minervini (INAF/IAPS), F.
Fuschino, M. Marisaldi (INAF/IASF-Bo and Bergen University),  A.
Giuliani (INAF/IASF-Mi), 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 G275404 at T0 = 2017-02-25
18:30:21.374 UTC, a preliminary analysis of the AGILE-GW fast data
processing procedure found no AGILE MiniCALorimeter (MCAL) event
candidates within a time interval covering -/+ 40 sec from the LIGO T0.
Two data acquisitions where collected about 45 sec before and 45 sec
after the LIGO T0; they show no significant transient candidate event.
A 3-sigma UL was computed for a 1 s integration time, on different
celestial positions within the G275404 error box, and varies from a
minimum of 5.3e-7 erg cm^-2 to a maximum of 10.3e-7 erg cm^-2, assuming as
spectral model a single power law with photon index 1.4. The AGILE-MCAL
instrument is a mini-calorimeter with a 4-PI FoV, working in the range
0.4 - 100 MeV.

Additional analysis of AGILE GRID and Super-Agile data is in progress.

V.M.  Lipunov, E. Gorbovskoy, N.Tyurina, V.Shumkov,
  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

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

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

MASTER OT J173532.70+103810.5 - possble new CV or?

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 17h
35m 32.70s +10d 38m 10.5s on 2017-02-25.80727 UT. (see GCN 20738
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 )
The OT magnitude in 'C' filter is 15.4m (limit 16.0m).

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

We have reference image without OT on 2015-01-27.94672 UT with magnitude
limit in 'C' filter 19.8m.

Spectral observations are required.

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 G275404.  We compared the candidate source directions of 3 temporally-coincident neutrinos to the pyCBC skymap, with the following parameters:

#  dt[s]  RA[deg] Dec[deg] E[TeV] Sigma[deg]
--------------------------------------------
1. -452.4 4.3	  35.8	   1.48	  2.25
2. -162.3 274.0	  77.0	   0.60	  0.19

(dt-time from GW; RA,Dec-sky location; E-reconstructed energy; Sigma-uncertainty of direction reconstruction)

The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES detected by IceCube within the 500 second window surrounding G275404 within the BAYESTAR skymap.

In addition, we are performing 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.  We will submit separate GCN circulars if coincident HESE or SN triggers are found.

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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 >.

The LIGO Scientific Collaboration and Virgo report:

The pycbc CBC analysis (Usman et al. 2016, CQG 33, 215004) identified
candidate G275404 during real-time processing of data from LIGO Hanford
Observatory (H1) and LIGO Livingston Observatory (L1) at 2017-02-25
18:30:21.374 UTC (GPS time:1172082639.374).

G275404 is an event of interest because its false alarm rate, as
determined by the online analysis, is 1.89e-07 Hz or about one in 2
months, passing our stated alert threshold of ~1/month. The event's
properties can be found at this URL:

https://gracedb.ligo.org/events/G275404

Based on preliminary matched-filter estimates of the masses and spins,
if astrophysical, there is a 100% 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 90% chance that the system ejected enough neutron-rich
material to power an electromagnetic transient.

One sky map with directional 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
sections of an annulus. The 50% credible region spans about 460 deg2 and
the 90% region about 2100 deg2. The luminosity distance is estimated to
be 280 +/- 80 Mpc (mean +/- standard deviation). This is the preferred sky
map at this time.

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

V.M.  Lipunov, E. Gorbovskoy, N.Tyurina, V.Shumkov,
  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

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

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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka was started inspection of the the  LIGO/Virgo G275404 50 
sec after notice time and 1626 sec after trigger time at 2017-02-25 18:57:27 UT.
The 5-sigma upper limit has been about 18.0 - 20.0 mag

The message may be cited.