GCN Circular 18738

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

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

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

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

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

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



MASTER-IAC  robotic telescope (MASTER-Net: http://observ.pereplet.ru, 2x4 
square degrees) located in IAC was pointed to the  LIGO/Virgo G211117 event 
(Possible Gravitational Wave Burst)  7975 sec after notice time and
1 days 58376 sec after trigger time at 2015-12-27 19:51:49 UT. Our first 
(180s exposure)  set we have 5-sigma upper limit has been about 20.0 mag 
(unfiltered).

MASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the LIGO/Virgo G211117 event 19726 sec 
after notice time and 1 days 70127 sec after trigger time at 2015-12-27 23:07:40 UT. On 
our first (180s exposure)  set we haven`t found optical transient  within 
LIGO error-box (ra=02 31 59 dec=+07 59 59 r=0.100000).
The 5-sigma upper limit has been about 20.2mag (unfiltered).
The message may be cited.


MASTER-Kislovodsk  robotic telescope (MASTER-Net: 
http://observ.pereplet.ru) located in SAAO was pointed to the  LIGO/Virgo 
G211117 event
9608 sec after notice time and 1 days 60009 sec after trigger time at 
2015-12-27 20:19:02 UT. On our first (180s exposure)  set we have
5-sigma upper about 15.3mag (unfiltered).

The full Coverage map  starting after trigger (47.5 % total probability 
- north + south segment) is  available here:
http://master.sai.msu.ru/static/G211117_MASTER_NET.png
This map includes both independently MASTER survey of the alert area on 
26th after , and Inspect images after the notice time (2015-12-27 17:38)

Four MASTER VWF  (very wide field FOV = 2 x 386 sq. degree, d=82 mm f/1.2) 
cameras at Kislovodsk and Canary Island cover 4.3 % of total probability 
field synchronously with Ligo trigger at 2015-12-26 03:38:53 UTC.
I.e we have  a set of 5 seconds images before, during and after trigger 
without time gaps.

The 3 sigma upper limit is about 11 mag at a single (5 seconds) image and 
12 mag at a coadd of 12 images with total exposure 60 sec.

Coverage map available here: 
http://master.sai.msu.ru/static/G211117_WF.png

We detected second OT during inspection.

MASTER OT J124246.31+111448.6 - possible QSO in active state not relaited 
with gravitational wave event.

MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 12h 
42m 46.31s +11d 14m 48.6s on 2015-12-28.28271 UT (error box  1 arcsec).
The OT unfiltered magnitude is 18.9m (limit 19.5m).

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

We have reference image without OT on 2015-12-28.25404 UT with unfiltered 
magnitude limit 20.0 m.
There is possible QSO  SDSS 124246.25+111449.0 inside our error box.
We have long story of the avout 2 magnitude variability this sources in 
Tunka nad Kislovodsk  MASTERs DataBase.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/124246.31111448.6.png

The reduction is continuated. 
This circular is an official product of the MASTER team.