TITLE: GCN GRB OBSERVATION REPORT NUMBER: 344 SUBJECT: X-ray/GRB 1SAX J0835.9+5118, BATSE Observation DATE: 99/05/24 17:13:18 GMT FROM: R. Marc Kippen at BATSE/UAH/MSFC R. M. Kippen, R. D. Preece, T. Giblin (University of Alabama in Huntsville) and C. Kouveliotou (USRA) report on behalf of the BATSE team: BATSE detected an untriggered event with significant flux (20-200 keV) coincident in time with the soft x-ray transient 1SAX J0835.9+5118 (Piro et al. GCN 333; Gandolfi et al. IAUC 7174). The BATSE on-board trigger system was disabled at the time, but the event was recorded in continuous data mode with 1.024 second temporal resolution. The BATSE location of (equinox 2000) R.A. = 141.1, Dec. = 56.8, with a statistical uncertainty radius of 9 deg, is consistent with that of the BeppoSAX wide field camera. The emission lasted ~8 s, with one main pulse (~2 s duration) preceded by a much weaker episode. The peak flux was 0.46 (-/+ 0.05) ph/cm2/s (50-300 keV; 1.024 s), with a total fluence of 8 (-/+ 3) E-7 erg/cm2 (>20 keV). The spectrum is consistent with a single power-law model (index -2.1 -/+ 0.4) or with curvature models with Epeak about 80 (-/+ 15) keV. Approximately 10% of the GRBs measured by BATSE have similar spectral properties, whereas the spectrum is significantly harder than that of a typical SGR burst. If this event is a gamma-ray burst, it ranks at the lower ~30% of the BATSE flux/fluence distribution. This notice is citeable. -eof-