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GCN Circular 4923

SGR 1900+14: Refined Swift-BAT analysis of the renewed activity
2006-03-26T19:22:53Z (18 years ago)
Scott Barthelmy at NASA/GSFC <>
G. Sato (ISAS), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), 
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
J. Tueller (GSFC), L. Vetere (ASDC)
on behalf of the Swift-BAT team:

Using the full data set from recent telemetry downlinks, we report
further analysis of Swift-BAT detection of SGR 1900+14 (trigger #202746)
(Vetere, et al., GCN 4922).  T90 is 48 +- 4 msec.  The partial coding
fraction is 33%.  The lightcurve is a single FRED-like peak wih a decay
of ~16 msec.  The BAT spectrum is well fitted with a blackbody model:
kT = 17.5 -7.9,+15.7 keV (90% confidence).  The reduced chi-squared
is 0.95 for 57 degrees of freedom.  The spectral parameters are consistent
with the HETE-2 observation of the 2001 middle-class burst of SGR 1900 
(see Fig.5 of Olive et al. ApJ 616 (2004) 1148 (astro-ph/0403162)).

There are 4 other BAT detections from this source (two before the 
original triggered detection, and two after):
   Date       Time       Comment
   2006-03-25 10:12:05   Roughly 4 times brighter than the 20:16:40 outburst
   2006-03-25 18:07:21   Roughly 2 times brighter than the 20:16:40 outburst
   2006-03-25 20:16:40   Triggered detection
   2006-03-25 23:34:08   Comparable to 20:16:40 in brightness
   2006-03-26 00:59:23   Comparable to 20:16:40 in brightness

We note that the 4th & 5th events occurred during TOO follow-up observations
of the SGR 1900+14 source.
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