TITLE:   GCN CIRCULAR
NUMBER:  13329
SUBJECT: GRB 120521C: MASTER optical limit 
DATE:    12/05/22 09:26:17 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, D.Denisenko, 
A.Belinski,
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov,  V.V.Chazov,
A.Kuznetsov
Moscow Lomonosov 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

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)



  MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB120521C  60 sec  after notice 
time and 715 sec after GRB time at 2012-05-21 23:34:03 UT in two 
polarizations. We haven`t found optical 
transient  within Swift BAT error-box (Baumgartner et al., GCN 13318) .
  The 5-sigma upper limit has been about 20.0 mag for mean time after 
trigger 1492s (total exposition 1370s).

The direct copy from MASTER DataBase is:

Pro.type   Date      time      Exp.time	Limit  Filt.	Tube.

Alert 	2012-05-21 23:34:03	130	17.7	P|	EAST
Alert 	2012-05-21 23:34:03	130	18.2	P-	WEST
Alert 	2012-05-21 23:34:03	130	18.2	P-	WEST
Alert 	2012-05-21 23:36:45	160	18.6	P-	WEST
Alert 	2012-05-21 23:36:45	160	18.1	P|	EAST
Alert 	2012-05-21 23:39:48	180	18.9	P-	WEST
Alert 	2012-05-21 23:39:48	180	18.4	P|	EAST
Alert 	2012-05-21 23:43:13	180	18.4	P|	EAST
Alert 	2012-05-21 23:43:13	180	19.0	P-	WEST
Alert 	2012-05-21 23:46:37	180	18.3	P|	EAST
Alert 	2012-05-21 23:46:38	180	18.4	P-	WEST
Alert 	2012-05-21 23:50:02	180	18.4	P|	EAST
Alert 	2012-05-21 23:50:02	180	19.1	P-	WEST
Alert 	2012-05-21 23:53:27	180	18.4	P|	EAST
Alert 	2012-05-21 23:53:27	180	19.1	P-	WEST
Alert 	2012-05-21 23:56:57	180	18.4	P|	EAST
Alert 	2012-05-21 23:56:57	180	19.0	P-	WEST 
AddWest 2012-05-21 23:34:03    1370     20.0    P-      WEST

The message may be cited.