TITLE: GCN GRB OBSERVATION REPORT NUMBER: 994 SUBJECT: GRB 010222 HST/Chandra TOO DATE: 01/02/27 00:17:33 GMT FROM: Shri Kulkarni at Caltech Dear Colleagues: This note is to inform you that, under the aegis of our HST AO-9 program, we have requested observations of GRB 010222 (GCN 959) with the Hubble Space Telescope and the Chandra X-ray Observatory. This burst with a bright optical (GCN 962, 963) and radio (GCN 968) afterglow appears to be particularly well suited for detailed studies of the afterglow and the circumburst medium. The Hubble observations involves six visits: STIS/NUV-MAMA (Feb 26), WFPC2 (Feb 28, March 9, March 15-19, TBD, TBD). In addition, a 30-ksec ACIS Chandra observation is expected to be conducted on March 6. We encourage parallel ground based observations of this burst so that it will become a very well studied afterglow. We will be supplementing the HST and Chandra observations with detailed multiwavelength observations at facilities to which our group has access (e.g. Keck, Palomar, MDM, HET). In the radio, we are undertaking observations with the VLA, JCMT, IRAM, Ryle, OVRO and Nobeyama. Shri Kulkarni, Titus Galama and Fiona Harrison on behalf of a large international GRB collaboration.