TITLE: GCN CIRCULAR NUMBER: 5850 SUBJECT: GRB061121: optical observations DATE: 06/11/24 17:54:56 GMT FROM: Alexei Pozanenko at IKI, Moscow Yu. Efimov, V. Rumyantsev (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed error box of GRB061121 (Page et al., GCN 5823) with Shajn 2.6m telescope of CrAO. A set of exposures was taken on Nov. 22 in B,R under poor weather conditions and a set of 22x180 s R-exposures on Nov.23. The afterglow (Page et al., GCN 5823; Yost et al., GCN 5824) is not detected in a single images of 60 s exposure on Nov.22 and clearly visible on a single images of 180 s on Nov. 23. For the analysis of Nov. 22 observation we take the best single image while for Nov.23 observation we use two combined images. Preliminary data reduction of the observations is following: Mid time Exposure, R_mag, Lim_mag (3 sigma) (UT) s Nov. 22.1309 1x60 n/d 20.60 Nov. 23.1040 11x180 21.37 +/- 0.05 23.55 Nov. 23.1329 11x180 21.47 +/- 0.06 23.49 Above estimations are based on USNO A2.0 star RA=09 48 57.46 Dec=-13 13 20.10 R=17.30. The combine image of the last epoch can be found in http://grb.rssi.ru/GRB061121/GRB061121_20061122_ZTSh_R This message may be cited.