GCN Circular 297
GRB 990506: Limits on the possible optical transient W. L. W. Sargent, T. A. Small, D. T. Frayer, S. R. Kulkarni, S. G. Djorgovski, J. S. Bloom (Caltech) report on behalf of the Caltech-CARA-NRAO Collaboration: A spectrum of the possible optical counterpart of GRB 990506 proposed by Vrba et al. (GCN 294) was obtained at the Keck-II 10-m telescope by Sargent and Small on 7 May 1999 UT. This object is a Galactic M-type star, and is thus presumably unrelated to the burst (cf. also Halpern, GCN 296). Images of the XTE/IPN error box were obtained at the Palomar 60-inch telescope by Frayer on 7 May 1999 UT, reaching considerably deeper than the DSS. No new optical objects brighter than the DSS limit were found. Furhter imaging observations are planned. This note can be cited.