TITLE: GCN CIRCULAR NUMBER: 7332 SUBJECT: GRB080205: optical observations DATE: 08/02/26 17:05:10 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), V. Biryukov (SAI, MSU), E. Klunko (ISTP), M. Andreev (Terskol Branch of Institute of Astronomy), A.J. Castro-Tirado (IAA-CSIC), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the afterglow (Li at al, GCN 7251), of GRB080205 (Palmer et al, GCN7250) with 1.5m telescope of Sayan observatory (Mondy) on Feb.05 in BR and Feb.06; with Zeiss-600 of Mt. Terskol observatory on Feb.05 in R; and with CrAO Shajn 2.6m telescope in BVRI on Feb.05, and on Feb.06. In CrAO observations we detected afterglow in R, V and not detected in B, I on Feb.05. We do not detect afterglow in any observations on Feb.06. T0+ Exposure R_mag (err) UL Site seeing (mean) 0.226 d 40x60 s n/d 21.1 Mondy 2.2" 0.379 d 30x60 s 22.26 (0.19) 23.0 CrAO 1.5" 0.409 d 20x90 s n/d 20.3 Terskol 2.0" 0.548 d 34x60 s 22.26 (0.15) 23.3 CrAO 1.4" 0.772 d 40x60 s n/d 22.4 CrAO 1.4" 1.530 d 123x60 s n/d 23.8 CrAO 1.7" Preliminary photometry reduction is based on USNO-B1.0 stars. Taking together KAIT (Li at al. GCN 7254) and ING (Rol et al. GCN 7258) observations one can suggest some episodes of a light curve of the GRB080205 afterglow: the steep decline of light curve with power law index about -1.6 between 537 s - 50 m (Li at al. GCN 7254), the shallow decay with power law index of -0.9 between T0+ 50m - 9h, plateau (or rebrightening) between T0+ 9h - 13h, and after then very steep decline. The data after ~50 m after burst onset is also compatible with a single power law with index -1.1 and a bump between 9h - 13h. Since we do not detect afterglow on Feb.06 (R>23.8) it is most probably that the previous phases of the light curve is not contaminated by a host galaxy. Our non detection of the afterglow in B-filter confirms the redshift less than ~4 (Oates at al. GCN 7253, Perley at al. GCN 7254). The message may be cited.