Skip to main content
New Swift-BAT/GUANO and IceCube Notice Types Available! See news and announcements

GCN Circular 333

BeppoSAX: A new fast X-ray transient
1999-05-20T15:55:58Z (25 years ago)
Luigi Piro at IAS/CNR Frascati <>
Luigi Piro, on behalf of the BeppoSAX team, reports:

Note: we have decided to distribute this info to the BeppoSAX GRB alert
list due to the potential association of these events (or some of those)
with GRB.

On May 20 at 2:02:58 UT a fast X-ray transient, which we designate 1SAX
J0835.9+5118, was detected by one of the BeppoSAX WFC (n.1).  The event
lasted about 10 s., with a peak flux of about 1 Crab in the 2-25 keV
range.  The position is (equinox 2000) R.A.=128.98, decl=51.31, with an
error radius of 3'.  No previously known X-ray source lies in the error
box.  At a preliminary analysis no simultaneous signal was detected by the
GRBM (40-700 keV).  Follow up observations are encouraged to investigate
the nature of this object. 

[GCN OP NOTE: I am allowing this BeppoSAX Circular on a new x-ray transient
to be distributed because (as pointed out) of the potential association
of this type of event with GRBs.  I realize this is outside the scope
of the Circulars in the strictess definition, but the potential is there
and it seems a small price to pay at this point in time.  It also serves
to explore this area for a future growth/expansion of the Circular service.
As always, I welcome comments from the community on the content and operations
of the Circular service.
CGRO-BATSE was in a "triggers disabled" mode (it was inside the N.American
Trigger Disable Box) during SAX-WFC transient time.  The LAD high voltage
was on and the SAX RA,Dec location was visible (not earth occulted), so any
data and analysis will be delayed until tomorrow to determine if BATSE actually
detected this event or not.]
Looking for U.S. government information and services? Visit