GCN Circular 1593
Subject
GRB 021004: Optical Decay
Date
2002-10-06T21:11:14Z (22 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern, N. Mirabal, E. K. Armstrong, C. C. Espaillat (Columbia),
J. Kemp (Joint Astronomy Centre and Columbia) report for the MDM GRB
follow-up team:
"Continued monitoring of the optical afterglow of GRB 021004 with
the MDM 1.3m yields the following measurements on On 2002 Oct 6 UT:
--------------------
UT R +/-
--------------------
02:41 19.84 0.03
07:03 19.91 0.02
11:39 20.00 0.02
--------------------
Here we used the revised calibration of Henden (GCN #1583) in which
the reference has star has R=15.52. Previous R magnitudes reported
in GCN #1578 would have to be decreased by 0.12 to match this reference.
The mean R-band decay between 8 and 48 hours as determined by the NOT and
MDM measurements can be described as a power law of slope -1.05, but with
highly significant deviations from a power law (Winn et al., GCN #1576)
that are robust against cross-calibration issues."
An updated decay curve will be maintained at:
http://www.astro.columbia.edu/~jules/021004.ps