TITLE: GCN CIRCULAR NUMBER: 41805 SUBJECT: EP250911a: SAO RAS optical observations DATE: 25/09/11 23:47:13 GMT FROM: Alexander Moskvitin at SAO RAS <mosk@sao.ru> A. Moskvitin, O. Spiridonova (SAO RAS) report on behalf of GRB follow-up collaboration. We observed the field of EP250911a (Liang et al., GCN 41788, Evans et al., GCN 41802) with the 1-m SAO RAS telescope Zeiss-1000 equipped with CCD-photometer. We obtained 9 x 300 sec. images in Rc band on September 11, 21:38:05--22:34:14 UT (t_mid - T0 = 13.12819 hours = 0.547008 days). The OT (Quirola-Vasquez et al., GCN 41790, Angulo et al., GCN 41793; Lai et al., GCN 41801) is clearly detected in the stacked image with the brightness of R = 21.90 +/- 0.11 (R_lim = 23.0 mag). This preliminary photometry is based on nearby SDSS stars (magnitudes were converted with the Lupton 2005 equations) and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41805. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...