GCN Circular 1576
J. Winn, D. Bersier, K.Z. Stanek (Harvard-Smithsonian Center for Astrophysics), P. Garnavich (Notre Dame) and A. Walker (CTIO) report: Images of the afterglow associated with GRB 021004 (GCN 1564) were obtained with the CTIO 4m + Mosaic Camera and the Fred Whipple Observatory 1.2m telescope beginning at Oct. 5.15 (UT). Preliminary analysis of the R-band images provide the following magnitudes assuming the USNO star noted in GCN 1573 has a magnitude of R=15.64: Oct. 5 UT R 03:00 19.10 04:46 19.21 05:55 19.24 07:23 19.25 08:43 19.23 09:53 19.31 These data indicate that the rapid decay (GCN 1573) has slowed considerably. The power-law index of the optical light between 15 and 22 hours after the burst is only 0.37. This behavior is similar to the bump seen in GRB 000103c which may have been due to a microlensing event (Garnavich, Loeb & Stanek 2000, ApJ, 554, 11). Monitoring this object at a moderate time resolution is urged. This message may be cited.