TITLE:   GCN CIRCULAR
NUMBER:  21875
SUBJECT: LIGO/Virgo G299232: Khureltogot observations
DATE:    17/09/12 19:49:39 GMT
FROM:    Alexei Pozanenko at IKI,Moscow  <grbgw.iki@gmail.com>

A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), S. Schmalz 
(KIAM), N. Tungalag (Research Center of Astronomy and Geophysics MAS), 
I. Molotov (KIAM) report on behalf of IKI-GW follow-up collaboration:

We observed  the field of  LIGO/Virgo trigger G299232 (LVC GCN 21693) 
and the error circle of IceCube candidate X1, hereafter ICX1 (GCNs 
21694, 21698) with  wide FOV VT-78a telescope of Khureltogot observatory 
starting on 2017-08-25 (UT) 15:24:13. We obtained several unfiltered 
images with the two time series, each centered to the position of 
localization reported in GCN 21694, and GCN 21698, respectively.
Preliminary results of our analysis of the fields are following.


Date       UT start  t-T0      Exp.   UL       FOV Center   Coverage
                  (Since G299232 (s) (5 sigma)  RA, Dec.     %
                    mid, days)                  degrees

2017-08-25 15:24:13  0.11289   60*60  19.3     27.1, 45.1  85.1
2017-08-25 16:32:52  0.16054   60*60  19.4     28.2, 44.8  78.3

Photometry is based on USNO-B1.0 stars (R2 magnitudes).
Total coverage of the error region of ICX1 (GCN 21698) is 85.7%. The map 
of the coverage can be found at
http://grb.rssi.ru/GW170825_G299232/LVC_IC_Khureltogot_v3.png

We found no new or unknown objects in the combined images up to the 
limits listed above.
We investigate all sources above S/N > 10 (~17m) and found no 
significant variability of the sources between the two epochs. We found 
no significantly more brighter sources which could be galaxies 
(including galaxy   2MASX J01571097+4715588 listed as Nearby Galaxies in 
the Localization Volume (GCN 21707))  than their R-magnitudes presented 
in the USNO-B1.0 catalog.