TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2747 SUBJECT: GRB040924: Afterglow magnitude at t=17.5hr DATE: 04/09/25 14:10:40 GMT FROM: Johan U. Fynbo at U.Copenhagen J. P. U. Fynbo (U. Copenhagen), A. Hornstrup (DSRI), J. Hjorth (U. Copenhagen), B. L. Jensen (U. Copenhagen), Michael I. Andersen (AIP) report on behalf or a larger collaboration: "We have observed the afterglow of GRB 040924 (Fenimore et al. GCN #2735; Fox et al. GCN #2734, GCN #2741) with the 2.56-m Nordic Optical Telescope on La Palma. By stacking 9 300sec exposures in the R-band with a mean epoch of Sep 25 5.25 UT we detect a source at the position of the candidate afterglow reported by Fox et al. Assuming a magnitude of R=19.1 for the nearby star U1050_00580520 we estimate that the afterglow flux is around R=22.1 17.5 hours after the burst. This implies the the lightcurve has become steeper than the slope of -0.7 during the first hour reported by Fox et al. (GCN #2741)." [GCN OPS NOTE: This circular was delayed 1.6 hr due to a change in the submiter's email domain.]