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GCN Circular 10052

GRB 091020: MASTER optical transient polarimetry
2009-10-21T05:15:37Z (15 years ago)
Vladimir Lipunov at Moscow State U/Krylov Obs <>
E. Gorbovskoy,D.Kuvshinov, V. Lipunov, V.Kornilov, D.Kuvshinov,
A.Belinski,  A. Krylov, N.Shatskiy, N.Tyurina, P.Balanutsa, V.V.Chazov,

Sternberg Astronomical Institute, Moscow State University

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

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

S.Yazev, K.Ivanov, N.M.Budnev
Irkutsk State University

Blagoveschensk Educational State University, Blagoveschensk

MASTER II robotic telescope (MASTER-Net:, 2x400 
mm, 8 square degrees, 2x16Mpx Apogee CCD) located
at Kislovodsk  was pointed to the  GRB 091020 (Racusin et al., GCN 10048) 
by internet   3422 s after the GRB time. The 
large delay  was caused with   technical problems on site.

We see bright optical counterpart (~17.5 mag) on the firrst images at UVOT 

We have 130  images with 180 sec synchronous exposition each and 19.5 
magnitude limit during ~4 hours in two polarization.

The power low decay with alpha ~= 1.3 during  2.5 hours is observed. 
This is the preliminary result.
The reduction is continued.

The message may be cited.

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