TITLE: GCN CIRCULAR NUMBER: 41310 SUBJECT: GRB 250809A: LCOGT Optical Upper Limits DATE: 25/08/10 00:29:39 GMT FROM: Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu> R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration: We observed the Swift GRB 250809A field (Parsotan et al., GCN 41303) with the LCOGT 1-meter Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on August 9, from 23:10 to 23:42 UT (corresponding to 6.28 to 6.85 hours after the GRB trigger time) with the Bessel R and I filters. We performed a series of 3x300s exposures in I-band and R-band. We do not detect an uncatalogued source within the Prompt Swift XRT error region (Evans et al., GCN 41304) in either band. The following 3-sigma upper limits are calculated using the USNO-B1.0 catalog as reference: R > 20.6 I > 20.3 These magnitudes are not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41310. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...