TITLE: GCN CIRCULAR NUMBER: 41870 SUBJECT: GRB 250916A: further SAO RAS optical observations DATE: 25/09/18 15:39:58 GMT FROM: Alexander Moskvitin at SAO RAS <mosk@sao.ru> A. Moskvitin (SAO RAS), A. Pozanenko (IKI), N. Pankov (HSE, IKI) report on behalf of GRB follow-up collaboration and IKI-GRB-FuN. We observed the field of the GRB 250916A (Fermi GBM team, GCN 41839; Arya et al., GCN 41843; Cheung et al., GCN 41855) with the BTA, 6-m telescope of SAO RAS equipped with SCORPIO-1 focal reducer. We obtained 3 x 60 sec. images in Rc band under mediocre weather conditions on September 18, 00:07:09--00:15:29 UT (t_mid - T0 = 1.4458 days = 34.6994 hours). The OT (Belkin et al., GCN 41847; Mohan et al., GCN 41858; Burkhonov et al., GCN 41860) at the redshift z = 2.015 (de Ugarte Postigo et al., GCN 41863) is clearly detected in the stacked frame with a brightness of R = 19.72 +/- 0.05. The preliminary photometry is based on PanSTARRS data on nearby objects (magnitudes calculated using the Lupton 2005 transformations) and does not take into account Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41870. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...