TITLE: GCN CIRCULAR NUMBER: 14893 SUBJECT: GRB 130603B: HST limits on an underlying supernova DATE: 13/06/13 21:18:52 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), A. S. Fruchter (STScI), J. Hjorth (DARK/NBI) and K. Wiersema (U. Leicester) report: We observed the location of GRB 130603B with HST/ACS and WFC3/IR. The host galaxy is clearly resolved as a disturbed spiral, and it appears that the GRB occurred close to a spiral arm that seems to have been tidally distorted or drawn out by interaction with a smaller neighbour. Our provisional analysis finds a point-source limit of F606W>27.6, corresponding to M_V~-14.3, at the location of the GRB. This is approaching a factor ~100 below what would be expected if there were a rising supernova comparable to SN1998bw, ruling out such an association for this burst. It also rules out some part of the parameter space of other radioactively-powered transients that have been proposed may accompany short GRBs. The position of the GRB lands on a region of extended emission in the F160W (H') filter of WFC3/IR. Another epoch scheduled for a few weeks from now will allow a deeper search for a counterpart through image subtraction. We thank the STScI director and staff for rapidly expediting these observations.