TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2830 SUBJECT: GRB 041006: Optical Observations DATE: 04/11/04 06:28:19 GMT FROM: Grant Williams at Steward Observatory G. Williams, X. Fan, A. Diamond-Stanic, M. Bayliss, D. Reichart, S. Shaw, A. Homewood, D. H. Hartmann, and M. Schwartz report on behalf of the MMTO, U. North Carolina, and SARA GRB teams of the FUN GRB collaboration: We observed the afterglow location (Da Costa et al., GCN 2765) of GRB 041006 (Galassi et al., GCN 2770) in Bg'VRc beginning 14.9 hours after the burst. Using the field calibration of Henden (GCN 2801), we report the following magnitudes: Start Mean Time Filter Exposure Magnitude Telescope Date Since GRB Time (sec) (1) (hours) x Exposures Oct 7.134 15.127 Rc 300 x 5 >19.3 0.9m SARA Oct 7.153 15.582 B 300 x 5 >18.2 0.9m SARA Oct 7.110 16.250 Rc 180 x 36 >19.3 0.6m MO(2) Oct 7.172 16.426 V 300 x 14 21.2+/-0.6 0.9m SARA Oct 7.280 18.408 g' 300 x 2 21.75+/-0.08 2.3m Bok (1) Limiting magnitudes are 2 sigma. (2) Morehead Observatory Previously reported in GCN 2799, the SARA observations are updated now that the field calibration is available. A light curve is available at: http://www.physics.unc.edu/~mbayliss/grbdata/grb041006lc.eps