GCN Circular 387
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.