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GCN Circular 5632

Subject
GRB 060926: MASTER: first minutes decay
Date
2006-09-27T15:54:15Z (18 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk

Sternberg Astronomical Institute, Moscow Union 'Optic'

MASTER  robotic system (http://observ.pereplet.ru)
responded to GRB060926 (Holland  et al., GCN Circ 5612) under the good 
conditions.
The first image was started at 2006-09-26 16:49:57 UT, 76 s  after the GRB
time (355 mm telescope, 6 square degrees FOV, 2.1'' per pix, CCD Alta U16).
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
We find faint OT on the first and on  the coadded images at 
position:

aplha = 17 35 43.66
dec   = 13 02 18.3
err = +- 0.7''

wich coincided with the Holland  et al.(GCN Circ 5612) OT position.

Our results:

   T-T_grb       mean time      exp_time           m (close to R)  S/N

  76 s - 106 s      91 s         30 s                 17.5+-0.3    4.5
  76 s - 360 s     218 s        5x30 s                18.2+-0.3     4
  76 s - 820 s     448 s       10x30 s                18.3+-0.3     4
  76 s - 1411 s    743 s       15x30 s                18.7+-0.3     4
1024 s - 1810 s  1417 s       10x30 s                  >19.7


We fitted these values with a powerlaw with a decay index of 0.69 up to 743 s. 
This is steeper then the powerlaw  OPTIMA-Burst
observations (GCN 5623, A. Stefanescu et al.).
The light curve is available at 
http://observ.pereplet.ru/images/GRB060926/lc.jpg .

JPG-Images are available.
Small part with OT:

First     - http://observ.pereplet.ru/images/GRB060926/GRB060926_1.jpg
Sum of  5 - http://observ.pereplet.ru/images/GRB060926/GRB060926_5.jpg
Sum of 10 - http://observ.pereplet.ru/images/GRB060926/GRB060926_10.jpg

The 2005 MASTER Survey Image
http://observ.pereplet.ru/images/GRB060926/GRB060926_2005.jpg
Full images:

http://pereplet.sai.msu.ru/nauka/i12.jpg
http://pereplet.sai.msu.ru/nauka/i12a.jpg
http://pereplet.sai.msu.ru/nauka/i12b.jpg

This work is supported by RFFI  04-02-16411 grant.
This message can be cited.
Mailto: lipunov@sai.msu.ru
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