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GCN Circular 318

Subject
GRB 990510 optical observations
Date
1999-05-12T03:20:47Z (25 years ago)
From
Krzysztof Z. Stanek at CfA <kstanek@cfa.harvard.edu>
K. Z. Stanek, P. M. Garnavich (Harvard-Smithsonian CfA), J. Kaluzny,
W. Pych (Warsaw Univ. Obs.) and I. Thompson (Carnegie Obs.) report:

We continued R-band observations with the 1.0-meter Swope telescope
at the Las Campanas Obs. of the optical transient associated with the
GRB 990510 on May 12.0 (UT). We find the OT declined by 1.4 mag since
May 11.0, consistent with a power-law decay index of -1.36,
considerably steeper than the index of -0.86 found from observations
between May 10.7 and 11.0 (Galama et al. GCN 313; Axelrod et al. GCN
315).  Compared to the star at RA 13:38:00.82 Dec -80:29:11.7 assumed
to be R=16.5 (USNO A2.0 catalog), we find the OT to be R=20.3 on May
12.0 (UT).  An updated light curve is available at
http://cfa-www.harvard.edu/~peterg/grb.html.

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