TITLE: GCN CIRCULAR NUMBER: 14256 SUBJECT: GRB 121128A: optical observations in Mondy observatory DATE: 13/03/04 20:20:57 GMT FROM: Alexei Pozanenko at IKI, Moscow A.Volnova (SAI MSU), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We report revised results of our observations in Mondy observatory (GCNs 14019, 14024) of the afterglow of GRB 121128A (Oates et al., GCN 14007; Japelj et al., GCN 14008). We re-processed data obtained on Nov. 28,29 and Dec. 02 based on full data set obtained. Nov. 28 t_start, filter, exp, T-t0, OT, err UT s d 10:27:30 R 4*30+16*60 0.23024 19.79 0.05 10:46:51 R 10*60 0.24047 19.85 0.04 10:56:58 R 10*60 0.24751 19.78 0.04 11:07:06 R 10*60 0.25454 19.96 0.05 11:17:14 R 8*60+12*40 0.26674 19.95 0.05 11:42:14 R 25*40 0.28132 20.07 0.05 11:59:13 R 30*40 0.29429 20.12 0.05 12:19:36 R 30*40 0.30845 20.06 0.04 12:39:58 R 30*40 0.32259 20.24 0.05 13:00:21 R 64*40 0.34488 20.32 0.04 Nov. 29 t_start, filter, exp, T-t0, OT, UL(3sigma) UT s d 10:16:58 R 6220 1.27406 n/d 23.3 Dec. 02 t_start, filter, exp, T-t0, OT, UL(3sigma) UT s d 10:47:17 R 4920 4.32854 n/d 21.2 The photometry is based on following reference stars 1442-0304687 20:02:23.58 +54:16:58.9 16.67 1442-0304744 20:02:29.58 +54:16:57.0 18.66 1442-0304807 20:02:36.33 +54:17:58.9 18.20 1443-0305750 20:02:37.10 +54:18:34.6 17.72 1443-0305710 20:02:32.72 +54:18:46.9 17.25 The combined light curve of our observations (this circular, GCN 14201 and GCN 14255) can be found at http://grb.rssi.ru/GRB121128A/GRB121128A_lc2.PNG Non-filtered photometry of Abastumani observatory (GCN 14201) is corrected to the R as d(C-R)=-0.034. One can see non-monotonous behavior of the lc between 0.4 -- 0.4 days after trigger, and probable jet brake between 0.6 and 1.3 days.