GCN Circular 1587
Subject
GRB 021004: Optical Observations
Event
Date
2002-10-06T07:10:41Z (23 years ago)
From
T.P. Prabhu at Indian Astro. Obs. <tpp@iiap.ernet.in>
D.K. Sahu, B.C. Bhatt, G.C. Anupama, T.P. Prabhu (Indian Institute of
Astrophysics, Bangalore) report on behalf of a larger collaboration:
GRB 021004 was observed with the HFOSC instrument on the 2-m Himalayan
Chandra Telescope on 4 and 5 October 2002. The magnitudes with respect to
the comparison star of Fox (GCN 1564) as calibrated by Henden (GCN 1583)
on October 4 are listed below:
October 4 R error
UT(center) (300 s)
16:34:36 17.13 0.01
16:44:03 17.20 0.01
16:52:29 17.24 0.01
17:01:16 17.21 0.01
17:09:26 17.28 0.01
17:18:12 17.39 0.01
18:04:37 17.69 0.01
19:48:36 17.90 0.02
20:33:36 18.06 0.02
22:05:58 18.20 0.03
23:36:22 18.46 0.05
B
(600s)
17:34:18 18.42 0.01
20:01:07 18.90 0.02
22:18:14 19.18 0.03
23:03:11 19.31 0.03
V
(400s)
17:42:32 18.01 0.01
20:14:38 18.50 0.02
22:40:30 18.77 0.03
23:14:33 18.78 0.03
These results supersede the ones reported in GCN 1581. Preliminary
magnitudes for October 5 are
UT R
17:38 19.38
22:10 19.70
The decay appears to have steepened following the bump noticed by Winn et
al (GCN 1576).
The spectra recorded with the same instrument on October 4 show the
redshift systems with z=1.38 and 1.60 (GCN 1582). The identification of
z=1.72 in GCN 1582 was erroneous and is regretted. On the other hand, we
confirm the presence of unidentified lines reported by Eracleous et al
(GCN 1579).
The message may be cited.