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GCN Circular 17518

GRB 150301B: MASTER early OT detection
2015-03-01T20:51:41Z (9 years ago)
Vladimir Lipunov at Moscow State U/Krylov Obs <>
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

E. Gorbovskoy, V. Lipunov,  V.Kornilov,
N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D.Kuvshinov,
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow 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.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, 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: 
located in SAAO was pointed to the  GRB150301.82 (Lien et al, GCN 17515) 
60 sec after notice time 
and 79 sec after trigger time at 2015-03-01 19:39:23 UT in two 
polarizations. On our first (10s 
exposure)  set we  found 1 optical transient within SWIFT error-box (ra=05 
56 37 dec=-57 58 35 r=0.050000).

                      T_start      RA            DEC     Exp     unfiltered
                          s                                      magnitude
  2015-03-01 19:39:23   79.0   05h 56m 39.94s  -57d 58m  10.0s     15.3

The error is about 0.5 arcsec. This position is coincidet with UVOT data.
We detected OT before maximum brightness.
The 5-sigma upper limit has been about 16.8 mag . The telegram is 
generated automatically.
We have number of the images after maximum in two polarizations. The 
reduction is continuated.
The message may be cited.
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