TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1717 SUBJECT: GRB021004, late time optical observations DATE: 02/12/02 16:51:59 GMT FROM: Vladimir Sokolov at SAO RAS T.A. Fatkhullin, V.N. Komarova, A.V. Moiseev (SAO RAS) report for the larger GOSH collaboration: The field of the GRB 021004 optical transient was observed with the SCORPIO instrument at the 6-m telescope of SAO RAS. The images were taken starting from 15:30 to 17:45 UT on Nov 29 and from 18.55 to 20.00 UT on Nov 30 under conditions of thin cirrus with seeing of about 1.2 arcsec in the first night and 1.5 arcsec in the second one. The V, Rc and Ic filters were used. The absolute astrometry was done relatively to USNO-B1.0 stars with internal error of 0.3 arcsec. We detect an object which coincides with the position of the optical transient (Henden et al. GCN #1592) within the astrometric error. Photometric calibration was performed using 6 standards (Henden et al. GCN #1630) in our FOV. The results of the photometry are given below: Data Filter Exp. OT mag. Aperture ------------------------------------------ 29 Nov Rc 15x180s 24.36+/-0.18 3.5 arcsec 29 Nov V 5x450s 24.53+/-0.18 3.5 arcsec 30 Nov Ic 14x120s >23.9 ------------------------------------------ At this stage it is not clearly whether the object is the pure host galaxy. Further observations are planned. Images can be seen at URL: http://www.sao.ru/~sokolov/GRB/FOLLOWUP/GRB021004/GRB021004.html This message may be cited.