TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1990 SUBJECT: GRB 030328: optical observations DATE: 03/03/29 15:15:55 GMT FROM: Denis Denissenko at IKI, Moscow R. Burenin, D. Denissenko, M. Pavlinsky, R. Sunyaev, O. Terekhov, A. Tkachenko (IKI); Z. Aslan, I. Khamitov, K. Uluc (TUG); U. Kiziloglu, A. Alpar, A. Baykal (METU); I. Bikmaev, N. Sakhibullin, V. Suleymanov (KSU) report: Error box of GRB030328 (HETE Trigger #2650, GCN 1978) was observed with 1.5-m Russian-Turkish Telescope RTT150 at Bakyrlytepe (TUBITAK National Observatory, Turkey) between Mar. 28.80 and 29.02 UT, starting appr. 9-10 hours after the burst. A set of 300-second exposures in BVRI Bessel filters was obtained under poor photometric conditions. We confirm the presence of the optical transient (OT) reported by Peterson and Price (GCN 1974). R magnitude of the OT on Mar. 28.952 (0.480 day after the burst) is estimated to be 20.35, assuming that Star B in GCN 1975 is R=16.1. This is brighter than the extrapolation of the power law from Price and Peterson (GCN 1977). OT is clearly visible in other filters in every 300-s exposure. The magnitudes in BVI will be obtained after we calibrate the field. The R image can be found at: http://hea.iki.rssi.ru/~br/r.gif Preliminary lightcurve in R: http://hea.iki.rssi.ru/~br/lc_r.ps This message may be cited.