GCN Circular 387
Subject
GRB 990712
Date
1999-07-12T23:07:26Z (25 years ago)
From
Kailash C. Sahu at STSci <ksahu@stsci.edu>
Gaspar Bakos (STScI and Konkoly Observatory), Kailash Sahu (STScI) and
John Menzies (SAAO) observing on behalf of the PLANET collaboration, and
Paul Vreeswijk (Univ. Amsterdam) and Filippo Frontera (ITESE, CNR, Bologna)
on behalf of the Amsterdam/Beppo-SAX-Bologna GRB follow-up team report:
GRB 990712 WFC error circle (Frontera et al. GCN #385) was observed with the
1m telescope of the South African Astronomical Observatory at Sutherland
on July 12.87 UT in R filter with an integration time of 900 sec. Comparison
with the Digitized Sky Survey (DSS) image shows a relatively bright source
at RA (2000) = 22 31 53.1, Dec (2000) = -73d 24' 29" (with a positional
uncertainty of about 1 arcsec) which is absent in the DSS image. Based on
the red magnitudes of thee USNO stars in the field, the estimated magnitude
of the new source is R = 17.85 +/- 0.2. Since the limiting magnitude of the
DSS image is at least 21, the new source is most likely the optical counterpart
of GRB 990712. Further observations are urged. A finding chart of the
optical counterpart can be seen at http://www.stsci.edu/~ksahu/grb990712.