TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1161 SUBJECT: GRB 011121: HST Scheduled DATE: 01/11/27 04:31:24 GMT FROM: Shri Kulkarni at Caltech S. R. Kulkarni, T. J. Galama and J. S. Bloom, California Institute of Technology reports on behalf of a large collaboration, "As a part of our AO-10 large program on GRBs we have triggered HST observations of GRB 011121. We will observe the optical afterglow of this GRB (GCN 1150) with WFPC2 on five different occasions (with the first visit being December 4, 2001). The sequence of observations is designed to either detect or place significant upper limits on possible underlying supernova component. We encourage overlapping ground-based observations over the next three weeks, particularly in the VRIZ bands."