TITLE: GCN CIRCULAR NUMBER: 18128 SUBJECT: GRB 150811A: SAO RAS optical observations DATE: 15/08/11 21:44:15 GMT FROM: Moskvitin Alexander at SAO RAS A. S. Moskvitin (SAO RAS, Russia) report on behalf of larger GRB follow-up collaboration: The field of the GRB 150811A (Evans et al., GCNC #18119) was observed with the Zeiss-1000, 1-m telescope of SAO RAS. The observations started since 13.6 hours after the trigger. 6 x 300 sec frames in Rc filter were obtained under the good weather conditions. The OT (Butler et al., GCNC #18120; Zheng, Wang and Filippenko, GCNC #18121; Kuin and Evans, GCNC #18122; Japelj, Guidorzi and Kobayashi, GCNC #18123; Perley and Cenko, GCNC #18125) is clearly detected in our stack image close to USNO-B1.0 star 0745-0762543. PSF photometry of the OT with DAOPHOT package gives R = 20.74 +/- 0.12 (T_mid - T0 = 13.911 hours). Photometry is based on the nearby USNO-B1 stars (R2 magnitudes). The magnitude of the OT is not corrected for the Galactic extinction.