GCN Circular 1334
Subject
GRB 020331: Candidate Optical Afterglow
Date
2002-04-07T06:37:50Z (23 years ago)
From
Derek Fox at CIT <derekfox@astro.caltech.edu>
D.W. Fox, P.A. Price, and S.A. Yost (Caltech), with R. Burruss
(Palomar Observatory), C.G. Tinney (AAO), and M. Begam and
B.P. Schmidt (RSAA, ANU) report:
"We have observed the error box of GRB 020331 (GCN #1315) with the
Palomar Hale 200-inch telescope + LFC at 2002 Apr 1.40 and 2.38 UT in
Sloan i'. Our observations cover the full burst localization to a
limiting equivalent R-band magnitude (derived by reference to a single
USNO star) of R ~ 23 mag. Visual inspection of the difference image
reveals one afterglow candidate at coordinates
RA: 13:16:09.54 Dec: -17:55:15.9 J2000
with an estimated uncertainty of 0.5 arcsec in each coordinate. The
candidate faded by 0.6 mag between the two observations, implying a
power-law decay index of alpha ~ 0.6, which would be unusual for a
normal afterglow. The candidate was R ~ 21 mag at the epoch of our
first observation, 17 hours after the burst trigger time of Mar 31.689
UT (GCN #1315).
The candidate is weakly detected on earlier images from the SSO
40-inch telescope, obtained Mar 31.78, which have a limiting magnitude
of R ~ 19.5 mag. The source is also detected on Mar 31.79 Ks-band
images from the AAT (c.f. GCN #1322). The candidate is not visible on
the second Digitized Sky Survey.
A finding chart for the candidate may be found at:
http://darkalf.caltech.edu/~pap/grb020331finder.ps
This message may be cited."