GCN Circular 983
K. Z. Stanek, P. Challis, S. Jha, R. Kilgard, J. McDowell (Harvard-Smithsonian CfA) and P. M. Garnavich (Notre Dame) report: We have obtained additional R-band data for the optical afterglow of the GRB010222 using the F. L. Whipple Observatory 1.2m telescope: HJD-2450000 UT R_c exp 1963.9457 010223 10:48 20.16+-0.07 600 sec Combined with our earlier R-band data (GCN 970), this indicates a power-law decay with a slope of 0.89, consistent with previous determinations (GCNs 973, 975). In the B-band, between 4.3 hours and 24.2 hours after the burst the afterglow dimmed by about 1.8 magnitudes: HJD-2450000 UT B exp 1962.9855 010222 11:46 18.46+-0.02 600 sec 1963.8173 010223 07:43 20.25+-0.10 600 sec This is consistent with no color evolution between B and R. Errors in the magnitudes are statistical only. The B-band magnitudes are relative to star "A" as marked in the finding chart at http://cfa-www.harvard.edu/cfa/oir/Research/GRB/, assuming its magnitude B=17.6. Reductions of additional data are under way. This message can be cited.