GCN Circular 13854

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

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

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

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

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

I.Zalozhnich,  A. Popov, A. Bourdanov
Ural Federal University

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)

Two MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Blagoveschensk and Tunka (Baykal lake) was pointed to the GRB 
121011A (Racusin et al., GCNC 13848) 51 sec after Trigger time at
2012-10-11 11:16:21.301 UT and 106 sec after Trigger time at
2012-10-11 11:17:14 UT in four polarizations (Yurkov et al., GCNC 13845).

Unfortunately the weather conditions were not very good at Tunka site.

We detected OT (Racusin et al., GCNC 13848; Kuroda et al. GCNC 13845;
Xin et al., GCNC 13847).

The preliminary results of the photometry calibrated to 0.8*R+0.2*B from 
USNO-B1.0:

     UTC	   Tmean-Tgrb Exp,s.    mag	s/n   magerr  filter  Site  Coadd

  11:16:21.0	56	10	>16.9	N/A	N/A	P/	Amur	No
  11:16:21.0	56	10	>16.9	N/A	N/A	P\	Amur	No
  11:16:21.0	96	80	>18.2	N/A	N/A	P/	Amur   Yes
  11:16:21.0	96	80	>18.2	N/A	N/A	P\	Amur   Yes
  11;18;29.0	200	40	>18.2	N/A	N/A	P/	Amur	No
  11;18;29.0	200	40	>18.2	N/A	N/A	P\	Amur	No
  11:19:20.429	255	50	17,38	5.9	0.18	P/	Amur	No
  11:19:20.461	255	50	17,17	5.8	0.19	P\	Amur	No
  11:20:21.37	321	60	16,89	8.9	0.12	P/	Amur	No
  11:20:21.396	321	60	16,9	8.1	0.13	P\	Amur	No
  11:21:32.001	397	70	16,77	11.1	0.10	P/	Amur	No
  11:21:32.02	397	70	16,81	11.5	0.09	P\	Amur	No
  11:22:52.945	487	90	16,59	14.7	0.07	P/	Amur	No
  11:22:52.998	487	90	16,49	15.8	0.07	P\	Amur	No
  11:24:33.654	599	110	16,42	18.7	0.06	P/	Amur	No
  11:24:33.678	599	110	16,57	16.6	0.07	P\	Amur	No
  11:26:34.121	729	130	16,55	17.6	0.06	P/	Amur	No
  11:26:34.144	729	130	16,5	18.4	0.06	P\	Amur	No
  11:28:54.944	885	160	16,69	18.1	0.06	P/	Amur	No
  11:28:54.947	885	160	16,7	15.5	0.07	P\	Amur	No
  11:31:45.672	1065	180	16,73	15.3	0.07	P/	Amur	No
  11:31:45.706	1065	180	16,72	14.2	0.08	P\	Amur	No
  11:35:11.589	1271	180	17,05	13.5	0.08	P/	Amur	No
  11:35:11.606	1271	180	17,03	11.1	0.10	P\	Amur	No
  11:38:37.563	1477	180	17,23	10.4	0.10	P/	Amur	No
  11:38:37.586	1477	180	17,25	10.3	0.11	P\	Amur	No
  11:42:12.62	1693	180	17,36	9.2	0.12	P/	Amur	No
  11:42:12.636	1693	180	17,48	7.7	0.14	P\	Amur	No
  11:45:38.297	1898	180	17,44	8.2	0.13	P/	Amur	No
  11:45:38.319	1898	180	17,44	7.2	0.15	P\	Amur	No
  11:49:03.877	2104	180	17,67	5.7	0.19	P/	Amur	No
  11:49:03.906	2104	180	17,73	5.0	0.22	P\	Amur	No
  11:52:29.982	2309	180	17,91	4.7	0.23	P/	Amur	No
  11:52:30.004	2309	180	17,82	5.4	0.20	P\	Amur	No
  11:55:55.714	2515	180	18,08	4.7	0.23	P/	Amur	No
  11:55:55.710	2515	180	18,04	3.4	0.32	P\	Amur	No



The mean (F/ - F\)/(F/ + F\) 100 < 2% during detection time.


The light curve between 200 sec and 6600 sec is very simmetrical in
log(F) - log (t) coordinates (like to bell) with parabolic low :

    m - m_max  = - A (log t/t_max)^2     (1)


A = 4.2 +/- 0.1



where t is time from GRB trigger in sec, t_max = 633+-11s, m_max = 
16.60+/-0.02 . We 
stress that this formulae does not depend on redshift.

The phenomenological formula discribed by Kocevski, D., Ryde, F., & Liang, E. 
(2003, ApJ, 596, 389) may be discussed in this situation but after z 
determination.

The preliminary light curve is available here:
http://master.sai.msu.ru/static/GRB/GRB121011_lc.gif

The preliminary approximation (formula(1)) is available here:
http://master.sai.msu.ru/static/GRB/GRB121011_lc_aproximation.png
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