GCN Circular 14269

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

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

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

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

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  GRB130306A 59 sec after Fermi 
trigger num 384306448 at 2013-03-06 23:48:24.313 UT, i.e. 157 sec before 
Swift  trigger time (Siegel et. al. GCN14266
Not found
 
 
).
The observations started on very high zenith distance about 85 deg.

SWIFT error box (Siegel et. al. GCN14266
Not found
 
 
) got on the edge of our FOV.  On 
our first (10s exposure) set we haven't found optical transient  within 
SWIFT error box. The 5-sigma upper limit has been about 13 mag.

Next time we pointed to BAT position at 2013-03-06 23:52:44.60 UT by 
SWIFT alert. On our first (20s exposure) set we haven't found optical 
transient  within SWIFT error-box  with upper limit 15.2m. On coadd image 
of 8 sets with total exposure 420 sec upper limit is 17.0m (5-sigma).

Galactic extinction in the direction of GRB 130306 is A_R=3.7, A_I=2.7
(from to Schlegel et al., 1998) and A_R=3.0, A_I=2.1 (according to
Schlafly et al., 2011).

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