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GCN Circular 3846

Subject
GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
Date
2005-08-21T19:34:25Z (19 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks
and T. Cline on behalf of the Konus-Wind team,
and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS
GRB team report:

A long soft GRB triggered Konus-Wind at T0=23954.512s UT (06:39:14.512).
It was also detected by INTEGRAL SPI-ACS. Because the burst was soft, 
the SPI-ACS response was weak, and precise triangulation of this burst 
is not possible. But the estimated time delay is consistent with the 
position of GRB 050525a, detected by Swift-BAT ~260 sec before 
Konus-Wind trigger (Page et al., GCN 3830; Cummings et al., GCN 3835).

The Konus-Wind GRB consists of two parts:
from ~T0-35s to ~T0+29s and ~T0+135s to ~T0+235s
and is much more intense than the Swift burst (precursor?),
which was weakly seen by Konus-Wind in background data.
The total burst duration is ~270 s.

The Konus-Wind light curve recorded in the background mode
is very similar to the light curve of the famous GRB 041219a
(Vestrand et al., Nature, 435, 178 (2005)):
weak precursor, main pulse at ~250 sec after it,
second pulse at ~150 s after main and then - weaker pulse(s).
The Konus-Wind light curve of this GRB can be seen
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB050825_T23954/

Based on these facts, we strongly suggest that this GRB is the main part 
of the GRB 050525a.
In this case the optical trainsient reported by Fox and Cenko (GCN 3029) 
and Wren et al. (GCN 3836) is in fact the prompt optical emission of
very long GRB 050525a (the total duration including Swift
precursor is ~500 sec).

We hope, that the further analysis of this event will clarify this issue.
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