TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2753 SUBJECT: GRB040924,optical observation DATE: 04/09/27 14:30:35 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Pavlenko, S. Sergeev, V.Rumyantsev (CrAO), A.Pozanenko (IKI) report: We observed the field of the optical afterglow candidate (Fox and Moon, GCN 2734) of GRB 040924 (=H3564, Fenimore et al., GCN 2735) in the R (Johnson) band with APOGEE 47 on the 38-cm Cassegrain telescope of the Crimean Astrophysical Observatory. The observations were started at Sep. 24, 20:21 UT (i.e. 8.48 hours after the burst) and continued up to Sep.24, 23.13 UT. The sum of the first 3 images (3x190-s) yield the limiting magnitude 19.7 +- 0.2. No optical counterpart at the position proposed by Fox and Moon was found. For the sum of last 7x240 images taken between Sep. 24 23:08 - 23:46 UT no counterpart fainter than 21.0 +- 0.2 was detected. The limiting magnitudes were estimated in comparison of the USNO-B1.0 stars as photometric sequences. The limits are in agreement with OT magnitude estimation in simultaneous observation of I.Khamitov et al. (GCN 2749). This message may be cited.