TITLE: GCN GRB OBSERVATION REPORT NUMBER: 993 SUBJECT: GRB 010222 DATE: 01/02/26 20:36:28 GMT FROM: Tetsuharu Fuse at Subaru Telescope, NAOJ During our Edgeworth-Kuiper belt object survey using Subaru telescope at Mauna Kea, we observed optical counterpart of the GRB 010222 detected by BeppoSAX using accurate coordinate reported by the Naval Observatory. Roughly estimated R-band magnitude was 18.9 +/- 0.1 at 22.642 (UT) using following stars PG1528+062A, SA104 338, and SA104 339. Due to the lack of standard star around 22.508 (UT), we conducted relative photometry and obtained 18.4 +/- 0.1 at 22.508 (UT). This preliminary result suggests the shallow slope for the lightcurve of GRB 010222. We would like to express our hearty thanks to URATA Yuji at the Science University of Tokyo for helping us to estimate appropriate exposure time. WATANABE, Jun-ichi National Astronomical Observatory of Japan KINOSHITA, Daisuke Graduate University for Advanced Studies FUSE, Tetsuharu National Astronomical Observatory of Japan KOMIYAMA, Yutaka National Astronomical Observatory of Japan FUJIHARA, Gary National Astronomical Observatory of Japan POTTER, Bob National Astronomical Observatory of Japan HARASAWA, Sumiko National Astronomical Observatory of Japan This message can be cited.