TITLE:   GCN CIRCULAR
NUMBER:  18281
SUBJECT: GRB 150910A: TSHAO optical observations
DATE:    15/09/11 19:27:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute),   A. 
Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. 
Pozanenko  (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of GRB 150910A (Pagani et al., GCN  18264)  with 
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory on 
Sep. 10 (UT) 18:02:59 -- 20:37:38.  We obtained several images in R and 
B filters.  In both filters the afterglow  (Pagani et al., GCN 18264; 
Zheng & Filippenko, GCN 18265) is clearly visible. Within 2.5 hours of 
observations we do not detect significant fading of the afterglow. The 
photometry of combined images are following

Date       UT start    t-T0     Filter  Exp.     OT       Err
                        (mid, days)      (s)

2015-09-10 18:08:20    0.42807  R       11*300   20.18 +/- 0.05
2015-09-10 18:02:59    0.42436  B       12*300   20.85 +/- 0.08

The photometry is based on nearby SDSS stars

SDSS_id            R(Lupton)
J002232.47+332751.3    16.29
J002236.24+332854.2    15.92
J002241.61+332836.1    16.23
J002248.33+332723.4    16.76
J002231.90+333004.8    16.93
J002225.39+332809.6    16.12
J002246.76+332716.9    17.63

Our photometry in R-filter is in agreement with  in subsequent 
observations (Moskvitin & Goranskij, GCN 18275).