TITLE: GCN CIRCULAR NUMBER: 41466 SUBJECT: GRB 250821A: LCOGT Optical Upper Limits DATE: 25/08/21 13:14:26 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 250821A field (Dichiara et al., GCN 41462) with the LCOGT 1-meter Sinistro instrument at the Siding Spring Observatory, Australia site, on August 21, from 12:00 to 12:32 UT (corresponding to 1.23 to 1.76 hours after the GRB trigger time) with the SDSS 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 41463) in either band. The following 5-sigma upper limits are calculated using the PanSTARRS catalog as reference: r > 23.0 i > 22.3 These magnitudes are not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41466. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...