TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3972 SUBJECT: GRB 050911: LCO limits on a variable source DATE: 05/09/13 02:52:04 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie Observatories), B. P. Schmidt (RSAA, ANU), A. M. Soderberg (Caltech), and A. Boss (Carnegie DTM) report: "We obtained second set of I-band observations of GRB 050911 with the du Pont telescope at LCO on 2005, Sep. 12.39 UT (18.5 hours after the burst). Digital subtraction of this observation from the one obtained 13 hours after the burst (GCN #3966) reveals no variable sources within the XRT error circle (GCN #3967) to a 3-sigma limit of I>21.9 mag in comparison to the UCAC2 star at RA=00:54:43.4587, DEC=-38:54:00.674."