[vsnet-grb-info 7442] GRB090305B: MASTER-net prompt optical short burst observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9004
SUBJECT: GRB090305B: MASTER-net prompt optical short burst observations 
DATE:    09/03/16 10:21:16 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc at observ.inetcomm.ru>

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

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

V.Krushinski, I.Zalognikh, T.Kopytova
Ural State University, Kourovka


S.Yazev, K.Ivanov
Irkutsk State University

There are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk 
with common FOW = 6000 square degrees (http://observ.pereplet.ru/).

One of the four  MASTER Very Wide Field Cameras located at Kislovodsk
(D=50 mm, 4x1000 square degrees, 11 Mpx) has observed  ~80% 1-sigma Fermi 
error box  (Colleen A. Wilson-Hodge, GCN 8972) with 1s exposure
during  all night: 7 hours befoure, during and 1 hours after GRB Time 
without time gap between images.


Our unfiltered images are calibrated relative to Tycho stars (V).
The magnitude limit of the each emage is  ~9.5 m at the edge of FOW.

We do not detect OT inside part of the error box  (Colleen A. Wilson-Hodge, GCN 
8972)  brighter than 9.2 mag before and after trigger time.
We  conclude in case that GRB inside our FOW that:

1). the optical fluence during the short 2 s GRBurst is limited by

                       ~<= 1 x 10E-8 erg/cm_2

excluding possible  host galaxy absorbtion.

The event fluence (8-1000 keV) in this time interval is
(2.7 +/- 0.2)E-06 erg/cm^2 (Colleen A. Wilson-Hodge, GCN
8972).

So:

2).  Optical-Fluence/Gamma-Fluence(8-1000 keV) ~ < 1/100

The same ratio for long GRB080319B is

Optical-Fluence/Gamma-Fluence(8 - 1000 keV) ~ 1/140

(Naked Eye GRB, Racusin, Karpov et al., Nature, vol.455, 183, 2008).


The film of our observations (from 10 s before and 15 s after GRB time) is 
available at

http://observ.pereplet.ru/images/GRB090305B/GRB090305B_full2.gif

White & black circles are the 1-sigma & 3-sigma+systematic (2 degrees) 
error boxes correspondingly. Black rectangle is the IPN error box (Palshin et al., private 
communication).

The FOWs of the 2 cameras are available at
http://observ.pereplet.ru/images/GRB090305B/FOW090305.png

The reduction is continued.

The message may be cited.

mailto: lipunov at sai.msu.ru