GCN Circular 316
Subject
GRB990510 optical observations
Date
1999-05-11T13:06:28Z (25 years ago)
From
Andrzej Udalski at Warsaw U. Observatory <udalski@sirius.astrouw.edu.pl>
G. Pietrzynski and A. Udalski (Warsaw University Observatory) report on
behalf of the OGLE microlensing survey team:
We monitored the optical counterpart of GRB 990510 (Vreeswijk et al.
1999, GCN 310) starting on May 10.992 UT, 1999 with the 1.3-m Warsaw
telescope at the Las Campanas Observatory (Chile). In total 17 V-band,
21 I-band frames were collected, covering about 10.25 hours. Exposure
time was 900 sec and 600 sec for the V and I-band frames, respectively.
The object is apparently variable -- its brightness faded by about 0.6
mag in the course of the night: from 19.45. to 20.05 in the V band and
18.50 to 19.15 in the I-band. Standard VI photometry of three, well
separated nearby constant stars (uncertainty +/-0.03 mag) is:
Delta X Delta Y \alpha_2000 \delta_2000 V I
from GRB position
Star 1 33.4"E 43.9"S 13:38:20.56 -80:30:31.9 15.617 14.636
Star 2 59.8"W 21.0"N 13:37:43.48 -80:29:26.7 16.203 15.161
Star 3 16.5"W 36.7"N 13:38:00.82 -80:29:11.5 17.014 16.094
Photometry of the optical counterpart of GRB 990510 and light curves are
available from the OGLE Internet archive:
http://www.astrouw.edu.pl/~ftp/ogle
[GCN OP NOTE: This circular was received at 12:42 11 May 99 UT,
but was not distributed due to not having a prior vetted account.]