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GCN Circular 344

X-ray/GRB 1SAX J0835.9+5118, BATSE Observation
1999-05-24T17:13:18Z (25 years ago)
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

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.

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