GCN Circular 1580
S. Balman (METU), H.Esenoglu (IU), M.Parmaksizoglu (TUG), Z. Aslan (TUG), U. Kiziloglu (METU) report on behalf of a larger collaboration (TUG, IKI, KSU): We have observed the optical transient (OT) of GRB 021004 (GCN #1564, 1565, 1568) with the 1.5m RTT150 telescope of TUG (TUBITAK National Observatory, Turkey) on Bakirlitepe between 19:30 and 20:30 UT on Oct 4 2002. We find: UT start exp_tim band magnitude 19:48:09 900 s R 17.82+-0.03 20:08:25 600 s I 17.18+-0.04 20:20:19 1200 s V 18.19+-0.11 using USNO-A2 magnitude estimates. Analysis of the full data set is underway. This message may be cited.