TITLE: GCN CIRCULAR NUMBER: 14019 SUBJECT: GRB 121128A: optical observation in Mondy observatory DATE: 12/11/29 17:50:57 GMT FROM: Alina Volnova at SAI MSU A.Volnova (SAI MSU), E. Klunko (ISTP), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of the Swift GRB 121128A (Oates et al., GCN 14007) with AZT-33IK telescope of Sayan observatory (Mondy). We took several images in R-filter of 60 s exposure on Nov. 28, between (UT) 10:27:30 - 13:43:09 under favorable weather conditions. We detected optical afterglow (Oates et al., GCN 14007; Japelj et al., GCN 14008) in stacked images. A photometry of some stacked image in the beginning of our observations and final stacked image is based on nearby USNO-B1.0 stars: t_start, T0+ (mid), filter, exp., OT, err (UT) d s 10:46:51 0.24047 R 10x60 19.95 +/- 0.06 13:00:21 0.34123 R 49x40 20.58 +/- 0.07 The photometry is still preliminary.