TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3792 SUBJECT: GRB 050813: Photometry of object in XRT error circle DATE: 05/08/13 16:31:55 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie Observatories) reports: "Inspection of DSS and 2MASS images reveals a single bright source on the SE edge of the XRT error circle (GCN 3790) of GRB 050813 (GCN 3788) located at: RA = 16:07:57.39 DEC = 11:14:42.95 Photometry of this source obtained from the 2MASS and USNO-B catalogs suggests that this object is most likely a star, and not a bright elliptical galaxy. In particular, J-K = 0.4 mag and B-K = 2.3 mag, as opposed to J-K ~ 1-1.3 mag and B-K ~ 4.3-5.4 mag for a typical elliptical galaxy at redshifts of 0.1-0.3 (similar to the redshifts of previous short bursts). The photometry is as follows: B = 16.61 mag R = 15.67 mag I = 14.72 mag J = 14.68 mag H = 14.37 mag K = 14.28 mag