This observation would appear to strengthen the reported variability of Object 1 and its identification with the GRB afterglow. Deeper images should urgently be obtained and monitoring should continue. The astrometric solution was obtained using 17 USNO catalog stars, m.e. 1998 Jan 01.8. This upper limit is at least a factor of 10 fainter than the optical transient associated with GRB 970508 at the same time interval.
More refined analysis is in progress.
Star B is the closest object to the detection claimed by Castro-Tirado et al. D is the comparison star mentioned by Galama et al. E and F are random galaxies in the same area, also given here as comparisons. We conclude that there is thus far no evidence for an optical transient associated with this gamma-ray burst down to significantly faint magnitude limits, similar to the cases of GRB 970815 and 970828. The galaxy is unrelated to the proposed counterpart.