GCN Circular 3403
Subject
GRB 050505, early TAROT observation
Date
2005-05-10T08:34:00Z (19 years ago)
From
Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse <atteia@ast.obs-mip.fr>
Klotz, A., Boer M. (OHP), and Atteia, J.L. (LAT) report:
We imaged the entire field of GRB 050505 (cf. Hurkett et al. GCNC 3360)
with the TAROT robotic telescope (D=25cm) located at the Calern observatory,
France. Observations started at 23:31:49 UT, 7 seconds after the GCN notice,
and 9.1 min after the GRB. The field had an elevation lower than 26 degrees
above horizon at the begining of the observations.
When we co-add series of 30s unfiltered images, we detect a source at the position
mentioned by S. Bradley Cenko et al. (GCNC 3366) until 23h47 UT.
As the redshift measured by Berger et al. (GCNC 3378) indicates a strong absorption
over the range of 6200-6500 A, we compared the flux of TAROT images (clear filter)
with the I band magnitudes of the USNO-B1 catalog. We find the following magnitudes:
2005-05-05T23:31:49 to 2005-05-05T23:39:25 I=18.2 +/- 0.2
2005-05-05T23:39:32 to 2005-05-05T23:47:08 I=18.4 +/- 0.2
2005-05-05T23:49:55 to 2005-05-05T23:59:39 I>18.8
The comparison with the I magnitude of 20.66 reported by Cenko et al. (GCN 3377)
6.4 hours after the GRB, indicate a slope of -0.7 for the temporal decay in I band.
Further information can be found at
http://www.cesr.fr/~klotz/grb050505/