GCN Circular 15176

E. Gorbovskoy,  V. Lipunov, D. Denisenko, V. Kornilov,  A. 
Kuznetsov, D. Kuvshinov, N. Tyurina, N. Shatskiy, P. Balanutsa, D.
Zimnukhov, V.V. Chazov
Lomonosov Moscow State University, Sternberg Astronomical Institute

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

K. Ivanov, S. Yazev, N.M. Budnev, O. Gres, O. Chuvalaev, V.A. Poleshchuk
Irkutsk State University

V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

V. Krushinski, I. Zalozhnich,  A. Popov, A. Bourdanov, A. Punanova
Ural Federal University

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

C. Mallamaci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB130903A 240 sec after notice 
time and 244 sec after GRB time at 2013-09-03 00:51:36 UT in two 
polarizations. Some delay was due to weather condition. On our first (40s 
exposure) set we haven`t found optical 
transient  within INTEGRAL error-box (S.Mereghetti et. al. GCN-15169 ).
The 5-sigma upper limit has been about 15.0 mag in each of polarization.

On best coadd image (with use of the first 12 sets on 6 in each of 
polyarization)  with total exposition 900 sec and middle time 504 after 
GRB time upper limit is 17.5 mag.

More detailed information in the following table:

   T_start  T_finish  T_mid     t_mid-t_trig  Exptime   Filter Limit  Coadd
---------------------------------------------------------------------------
00:51:36  00:52:16  00:51:36     264 s        40 s       P|   15.0     no
00:51:36  00:52:16  00:51:36     264 s        40 s       P-   15.0     no
00:51:36  00:52:16  00:51:36     264 s        80 s    P| + P- 15.5      2
00:51:36  01:00:16  00:55:56     504 s       450 s       P|   17.0      6
00:51:36  01:00:16  00:55:56     504 s       450 s       P-   17.0      6
00:51:36  01:00:16  00:55:56     504 s       900 s    P| + P- 17.5     12

P-  and P| is a RA and DEC orientated polaroids.

The message may be cited.