TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3100 SUBJECT: GRB 050315: Optical afterglow identification DATE: 05/03/16 09:41:52 GMT FROM: Edo Berger at Carnegie Obs Dan Kelson and Edo Berger (Carnegie Observatories) report: "On 2005, March 16.347 UT we imaged the XRT error circle of GRB 050315 (GCN 3097) with the newly-comissioned LDSS3 instrument on Magellan/Clay in the r-band filter. Within the 6" radius error circle we find a single bright object which is not present in the DSS at coordinates (J2000): RA = 20:25:54.1 DEC = -42:36:02.2 with an uncertainty of about 0.5" in each coordinate. We consider this object to be the optical afterglow of GRB 050315."