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
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).
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