GCN Circular 4159
V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), and A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the SXC error box of HETE-2 GRB051021a (Yoshida et al., GCN4116) with 0.6 m telescope (Crimean laboratory of SAI) equipped with FLI IMG-1001E camera. The series of 60 sec R-band exposures were taken between October 21, 21:19:01 and October 22, 00:23:24. We clearly detect the optical afterglow (Fox et al. GCN4120, Swan et al. GCN4120) on stacked image. Coordinates of the source are RA=01 56 36.37 Dec=+09 04 03.27 (J2000) with uncertainty of 0.5 arcsec. Preliminary photometry of the stacked image is following: Mid time (UT) Exposure R Oct. 21 22:51 146x60 21.9 +/-0.2 Photometry and astrometry of the source are based on USNO-A2.0. Stacked image can be found in http://grb.rssi.ru/GRB051021a/. Taken R-band magnitudes (GCNs 4120, 4123) and upper limit reported in GCN4138 (Eastman et al.) our results is compatible within statistical error with single power-law decay light curve alpha ~ -1.6. Also extrapolating backward J-band (Reichart et al., GCN 4144) observations to our epoch (Oct. 21 22:51) we found R-J ~ 1.0 which do not imply a high redshift source. This message may be cited.