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GCN Circular 9830

GRB 090820: MASTER-Net optical polarization observations
2009-08-20T16:35:57Z (15 years ago)
Vladimir Lipunov at Moscow State U/Krylov Obs <>
E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,
D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov
Sternberg Astronomical Institute, Moscow State University

K.Ivanov, S.Yazev
Irkutsk State University

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

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

There are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk 
with common FOW = 2000 + 1680 square degrees (

Four   MASTER Very Wide Field Cameras located at Kislovodsk
(4 Carl Zeiss Planar T* 85/1.4 ZF, 4x420 square degrees, 11 Mpx, 22" per 
pix  with 4 polarizers) responded to 
the bright  GRB 090820 (Fermi TRIGGER_NUM:272421498, V. Connaughton, GCN 
9829), producing images beginning 9 s after the GRB Time (first alert notice).

We took 1300 images with 5 sec exposition in different polarizations.
Individual images have limiting magnitudes~11.

Our unfiltered images are calibrated relative to Tycho stars (V) and very close 
to V band.
Other observations are required for independ error box elaboration.

The reduction is continued.

The message may be cited.

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