GCN Circular 17558

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

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

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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

V.Krushinsky,
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 ( Lipunov et al., Advances in Astronomy, vol. 
2010, pp. 1-7, MASTER Global Robotic Net, 2010) 
located in Kislovodsk was pointed to the  GRB150309A 21 sec after notice 
time and 96 sec after trigger time at 2015-03-09 23:04:45 UT in two 
polarizations. On our first (20s exposure)  set we not  found  optical 
transient within SWIFT error-box (Cummings et al GCN 17553
Not found
 
 
) brighter then 
17.2

Before this, the MASTER serial pointed to  FERMI (trig. N 447634793) 
coordinates. Due to this pointings we have a two images from MASTER VWF 
very wide fild camera  obtained at 2015-03-09 23:00:34 i.e. 152 sec before 
SWIFT BAT and  44 sec after FERMI GBM trigger times. We not found new OT 
on this 5 sec exposure images with upper limit 12.0 at SWIFT position.

Table 1. GRB 150309A MASTER optical upper limits.

Tstart  Tst-T0 Tmid-T0 Expt Mlimit  Instrum.   Coadd.
23:00:34  -152    -149    5 12.0    MASTER VWF   no
23:04:45    98     108   20 17.2    MASTER II    no
23:04:45    98     559  780 19.3    MASTER II    10
23:20:20  1033    2363 2160 20.0    MASTER II    12

T0 - is a SWIFT trigger time.

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