TITLE: GCN GRB OBSERVATION REPORT NUMBER: 339 SUBJECT: X-ray/GRB 1SAX J0835.9+5118, Optical Observation DATE: 99/05/21 15:55:42 GMT FROM: Arne A. Henden at USNO/USRA A. Henden (USRA/USNO), F. Vrba, C. Luginbuhl, R. Stone, B. Canzian, J. Munn, S. Levine, H. Guetter (USNO) report: We monitored the field of the BeppoSAX fast X-ray transient 1SAX J0835.9+5118 (Piro GCN 333, Gandolfi et al., IAUC 7174) on the night of UT 990521 with the USNO 1.0-m telescope. The night was photometric during the observations, though cirrus arrived shortly thereafter. Enough standards were observed to calibrate the field in BVRI. The calibration file can be found on ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/j0835.dat where 19 Landolt standards were used for the photometric calibration, and USNO-A2.0 was used for the astrometric calibration. Stars brighter than V=13.5 are saturated and are included only as field identifiers. A report on our deeper imagery will be posted later. [GCN EDITOR'S NOTE: J.Greiner would like the GRB community to know that due to a recent computer theft incident and subsequent computer replacements operations, his GRB web site has moved to a new URL: http://www.aip.de/People/JGreiner/grbgen.html]