TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2171 SUBJECT: GRB030329, SPM optical observations DATE: 03/04/25 11:53:46 GMT FROM: Sergej Zharikov at OAN IA UNAM S. Zharikov, G. Tovmassian, M. Richer (OAN SPM IA UNAM, Ensenada, Mexico) report: We have observed the OT GRB030329 found by B.Peterson and P.Price (GCN 1985) using 1.5m telescope of OAN-SPM Observatory, BC, Mexico. A set of exposures in UBVRI Bessel filters was obtained 24 April and 25 April under photometric and good seeing conditions. Standard stars RU 149 from Landolt's catalogue were used for photometric calibrations in the each night. The results of photometry of summed images are following: 24 April Texp. Filter Mag. UT 5:50 5400sec U 21.76(12) UT 6:56 4800sec B 21.51(6) UT 5:54 2400sec V 20.73(4) UT 6:30 3300sec R 20.17(5) UT 6:10 2400sec I 19.90(5) Corresponding color indexes are U-B = 0.25(14) B-V = 0.78(7) V-R = 0.56(6) R-I = 0.27(6) 25 April Texp Filter Mag. UT 5:10 5400sec B 21.63(5) UT 7:30 3600sec V 21.72(4) UT 6:17 2400sec R 20.16(5) UT 8:00 3600sec I 20.01(5) The magnitudes no changed during those nights. The OT source looks like a point-like object. Two faint extended objects detected nearly OT position. O1: 10:44:50.03 J2000 +21:31:10 R~22.5 distance from OT is about 7" O2: 10:44:49.4 J2000 +21:31:14 R~22.9 distance from OT is about 9" This message may be cited