GCN Circular 1578
Subject
GRB 021004: Optical Observations
Event
Date
2002-10-05T12:08:24Z (23 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern, E. K. Armstrong, C. C. Espaillat (Columbia),
J. Kemp (Joint Astronomy Centre and Columbia) report for the
MDM GRB follow-up team:
"We observed the optical afterglow (Fox, GCN #1564) of GRB 021004 with
the MDM 1.3m in BVRI. On 2002 Oct 5 UT, we measure the following
preliminary magnitudes:
--------------------
UT R +/-
--------------------
03:02 19.06 0.06
03:36 19.17 0.05
04:26 19.24 0.03
04:51 19.30 0.04
05:15 19.30 0.03
05:39 19.25 0.03
06:10 19.33 0.03
06:34 19.30 0.04
06:56 19.32 0.03
07:19 19.42 0.03
07:42 19.31 0.03
08:05 19.31 0.03
08:28 19.31 0.03
08:50 19.27 0.03
09:13 19.29 0.03
09:41 19.34 0.03
10:03 19.34 0.03
10:41 19.41 0.03
11:04 19.39 0.03
11:26 19.41 0.04
11:50 19.39 0.04
--------------------
We employed the Weidinger et al. (GCN #1573) revised calibration star.
These measurements are consistent with and extend the steepening light
curve that they saw. The combined NOT and MDM points indicate a decay
slope alpha = 1.16 +/- 0.07, but there are possible fluctuations of the
type referred to by Winn et al. (GCN #1576) in our data that are
contemporaneous with theirs.
An updated decay curve is available at:
http://www.astro.columbia.edu/~jules/021004.ps
An equal number of images in each of B, V, and I were obtained, and will
be analyzed subsequently."