TITLE: GCN GRB OBSERVATION REPORT NUMBER: 985 SUBJECT: GRB010222, possible increase of optical decay slope DATE: 01/02/24 18:59:09 GMT FROM: Nicola Masetti at ITeSRE,CNR,Bologna N. Masetti, E. Palazzi (ITeSRE, CNR, Bologna), E. Pian (Oss. Astron. Trieste), A. Zacchei, A. Magazzu, M. Pedani, F. Ghinassi (TNG) and M. Mignoli (Oss. Astron. Bologna), on behalf of a larger collaboration, report: "We observed the optical transient (Henden, GCNs #961, #962) associated with GRB010222 (Piro, GCNs #959, #960) in the R band with TNG+Dolores on 2001 Feb. 24.236 UT (i.e. ~2 days after the GRB). The total exposure time was 4 minutes; seeing was 0.9 arcsec. Using star `A' by Stanek et al. (GCN #970) as reference, we note that our measurement, R = 20.88 +- 0.03, is ~0.4 mag fainter than the extrapolation of the t^{-0.9} decay measured by Price et al. (GCN #973), Fynbo et al. (GCN #975) and Stanek et al. (GCN #983). The power-law decay between our TNG measurement and that made in the R filter by Stanek et al. (GCN #983) on Feb. 23.45 has an index ~1.3. Thus, our data seem to suggest that a break occurred at ~1 day after the GRB in the R-band light curve of the afterglow. Further observations are strongly encouraged to confirm (or reject) this result.". This message can be cited.