TITLE:   GCN CIRCULAR
NUMBER:  14412
SUBJECT: GRB 130420B: MASTER-Net optical observations
DATE:    13/04/20 13:51:33 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>

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

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

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

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

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

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 Blagoveschensk was pointed to the  GRB130420B (Oates et. al 
GCN 14411)  44 sec s after notice time and 63 sec after GRB time at 
2013-04-20 12:57:34.948 UT in two polarizations. On 
our first (10s exposure) set we haven`t found optical transient  within 
SWIFT error-box (ra=12 12 28 dec=+54 23 24 r=0.050000).
The 5-sigma upper limit has been about 16.0 mag.
The message may be cited.