TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4178 SUBJECT: GRB051028: optical observations DATE: 05/10/29 17:37:08 GMT FROM: Patrizia Ferrero at TLS Tautenburg P. Ferrero, D. A. Kann, S. Klose, and C. Hoegner, Thueringer Landessternwarte Tautenburg, report: We observed the entire error box of GRB 051028 (HETE trigger 3951; Hurley et al. 2005, GCN 4172) with the 1.34-m Tautenburg Schmidt telescope equipped with the prime focus CCD camera on October 28, 2005. Sky conditions were very good. We obtained 6x180s I-band images (mean time Oct. 28.716 UT), 6x180s R-band images (mean time Oct. 28.739 UT), 6x180s V-band images (mean time Oct. 28.77 UT) and a final set of 60x180s I-band images (mean time Oct. 28.898 UT), corresponding to 3.58, 4.12, 4.88 and 7.94 hours after the burst, respectively. In our stacked images we clearly detect the afterglow candidate (Jelinek et al. 2005, GCN 4175; Pandey et al. 2005, GCN 4176) in all bands. A preliminary estimation of the afterglow magnitude on the first six co-added I-band images gives I~19, in comparison with the USNOB.1 star 1377-0047752 at R.A. (J2000)=01h 48m 15.974s and Decl.=+47d 45' 02.34" (Monet et al. 2003). Further analysis is in progress. This message may be quoted.