TITLE: GCN CIRCULAR NUMBER: 41000 SUBJECT: GRB 250706A: SAO RAS optical observations DATE: 25/07/07 03:57:27 GMT FROM: Alexander Moskvitin at SAO RAS <mosk@sao.ru> A. Moskvitin and O. Spiridonova (SAO RAS), report on behalf of a GRB follow-up collaboration. We observed the field of the GRB 250706A (Moss et al., GCN 40988) with SAO RAS 1-m telescope Zeiss-1000 equipped with CCD-photometer. We obtained 20 x 300 sec. images in Rc band on July 6, 20:04:37--22:41:35 UT (t_mid - T0 = 5.5764 hours) under a good weather conditions and the seeing of 1".6. In the XRT error circle (Moss et al., GCN 40988) we detected a bright stellar-like source with the coordinates R.A. = 18:56:04.3, Dec. = +32:19:13.5 (J2000.0) also presented in the archival images. After the PSF subtraction of this bright star we did not detect any significant sources down to the limiting magnitude of R_lim = 23.0. (based on the nearby USNO-B1.0 stars and not corrected for the Galactic extinction) Additionaly we divided whole set into two 10 x 300 sec. subsets (1st: t_mid - T0 = 4.9217 hours, 2nd: t_mid - T0 = 6.2393 hours) and found no significant residuals between two stacked images and no variability of the mentioned bright star within 0.01 mag. between two epochs. This results are in agreement with OT non-detection by Moss et al. (GCN 40988); Mohan et al. (GCN 40990) and Wu et al. (GCN 40998). View this GCN Circular online at https://gcn.nasa.gov/circulars/41000. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...