TITLE: GCN CIRCULAR NUMBER: 15237 SUBJECT: GRB 130831A: Maidanak optical observations, possible emerging Supernova DATE: 13/09/21 12:04:06 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Volnova (IKI), B. Hafizov (UBAI), O. Burhonov (UBAI) report on behalf of larger GRB follow-up collaboration: We continue observation of the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with AZT-22 telescope equipped with SNUCAM at Maidanak observatory. A preliminary photometry of combined images obtained on Sep. 16 is following: T_start T0+ Filter, Exposure, OT (UT) (mid, d) (s) 2013-09-16T19:00:13 16.28 R 14x300 22.77 +/- 0.07 The photometry is based on SDSS stars (see GCN 15190). This is brighter than we obtained on Sep. 9 (23.11 +/- 0.06) and on Sep. 15 (22.87 +/- 0.08). We suggest the observed re-brightening is an emerging Supernova associated with GRB 130831A. A preliminary lc of the afterglow+SN of GRB 130831A can be found in http://grb.rssi.ru/GRB130831A/grb130831A_lc_preliminary.PNG