GCN Circular 6508
Subject
GRB 070610: OPTIMA-Burst detection of continued strong flaring activity
Event
Date
2007-06-12T01:47:18Z (18 years ago)
From
Alexander Stefanescu at MPE <astefan@mpe.mpg.de>
A. Stefanescu (1), A. Slowikowska (2)(3), G. Kanbach (1), S. Duscha (1),
F. Schrey (1), H. Steinle (1), Z. Ioannou (4) of the OPTIMA-Burst Team
report the following:
(1)=MPE, Garching, (2)=FORTH, Heraklion (3)=NCAC, Torun (4)=Univ. of Crete
"OPTIMA-Burst at the 1.3m Skinakas Observatory, of the University of
Crete, Greece continued observations of the source reported on earlier
in GCN 6492 (Stefanescu et al.), GCN 6501 (de Ugarte Postigo et al.)
and GCN 6505 (Kann et al.)
Observations started at 20:40 UT, 0.991 days after the burst. Taking the
same reference star as Kann et al. (GCN 6505), we detect the source with
the following magnitudes in our CCD frames:
UT_mid T_GRB [d] t_exp I mag
20:42:38 0.99319 300 19.2
20:57:26 1.00347 1200 17.0
21:25:37 1.02304 300 20.7
21:31:19 1.02700 300 21.2
After this time, observations with the high-time-resolving main
instrument of OPTIMA-Burst commenced. The following describes a
quick-look analysis of 83min of data, binned to a time-resolution of 10s.
During it's low brightness periods, the source was not detected above
the noise in our photon counting detectors. However, we detected bright
flares with pronounced substructure around the following times:
UT T_GRB [d] duration (approx) peak brightness (preliminary!)
22:09 1.052 3.0 min 18.0 mag
22:20 1.060 7.5 min 17.4 mag
22:40 1.074 5.9 min 17.6 mag
In addition to these we detected 5 smaller flares at the 2.5 to 3 sigma
level, each lasting for about 1 minute and having a peak brightness of
about 19.7 mag.
Further observations and further analysis is in progress.
Since it seems strong variability is still in progress, we strongly
recommend further observations."
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