GCN Circular 13162

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

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

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

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 
Tunka was started to survey IPN error box of the long/intense  GRB 120328B 
(Hurley et al., GCN Circ 13157
Not found
 
 
)  6 hours after GRB time at 2012-03-28 13:26:23 UT.
The eroor box was arised. The weather was changed. The better images limit 
was about 18 unfiltered magnitudes.

There is no OT inside IPN error box with 18 mag limit.

MASTER-Tunka auto-detection system discovered faint OT source (4.1 sigma) 
at (RA, Dec) = 15h 06m 01.01s +28d 41m 59.8s on 2012-03-28.59161 UT (~7h45 
min after GRB time)  outside error IPN box (see map 
http://observ.pereplet.ru/images/GRB120328B_IPN_map_MASTER$ 
GRB120328B_IPN_map_MASTER.png ).
The OT unfiltered magnitude is 17.9m (limit 18.0m).

The OT is marginally seen at several images 2 images. There is no minor 
planet at this place.

There is no known source at this place.

We have reference image without OT on 2011-06-04.67172 UT with unfiltered 
magnitude limit 20.1m.

Follow up observations will be continuated.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/150601.01284159.8.png


The message may be cited.