TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2775 SUBJECT: GRB041006, optical observation DATE: 04/10/07 00:17:13 GMT FROM: Alexei Pozanenko at IKI, Moscow B. Kahharov, I. Asfandiyarov, M. Ibrahimov, D. Sharapov (UBAI), A.Pozanenko (IKI), V.Rumyantsev (CrAO), G.Beskin (SAO) report: We have observed the filed of error box of GRB041006 (HETE #3570, M. Galassi, et al. GCN 2770) starting Oct.6 15:49 (UT) with 1.5m telescope of Mt.Maidanak High-altitude Observatory. Several BVRI images were taken between 15:49 and 16:51. We confirm a fading source found by G. Da Costa et al. (GCN 2765). Preliminary reduction of the data against the USNO-A2.0 catalog yield the following OT magnitudes in R UT exposure mag err 15:49 180 s 18.7 (0.09) 16:46 300 s 19.1 (0.10) The magnitudes assume a temporal decay index about 1.5 which is stepper than found by P.A. Price, et al. (GCN 2771) and may indicate a brake of a light curve of the OT. This message may be cited.