TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1608 SUBJECT: GRB 021004: HST/STIS spectroscopic observations DATE: 02/10/09 03:45:52 GMT FROM: Andrew S. Fruchter at STScI K. Sahu, A. Fruchter, I. Burud, and K. Sembach (STScI) report for the larger GOSH collaboration: GRB 020411 was observed from 14:00 to 23:00 UT on Oct 6 using the STIS CCD spectrograph and G430L grism, and the NUV MAMA and prism. The CCD spectrum shows two prominent absorption features, at 404.1 nm and 401.1 nm. The first of these agrees well with a previously reported feature that has been identified as Lyman alpha at z=2.323. The second absorption feature would then appear to be Si III at z=2.324, which would imply an offset of order 100 km/s in the restframe between the ionized and neutral components. The NUV MAMA prism observation shows a break shortward of approximately 303.0 nm, which would correspond to the Lyman limit of the z=2.323 system. Calibration of both the CCD and NUV MAMA observations may be improved when all files from the observation are available to us.