[vsnet-grb-info 2812] Swift-BAT trigger is GRB 060203

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4649
SUBJECT: Swift-BAT trigger is GRB 060203
DATE:    06/02/04 04:32:04 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

J. Cummings (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the partial data set from T-60.0 to T+123.1 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060203 (trigger #180151)
(Retter, et al., GCN 4641).  The BAT ground-calculated position
is RA,Dec = 103.468,+71.841 deg {06h 53m 52s,+71d 50' 28"} (J2000)
+- 2.8 arcmin, (radius, sys+stat, 90% containment).  This is 2 arcmin
from the ground-calculated XRT position in Circ 4644.  The partial coding
was 50%.
 
The burst has a single broad shallow peak starting at T-20 to T+65 sec.
We are waiting for more data to be downlinked and may find that this burst
lasts longer than our current estimate.  T90 (15-350 keV) is (83 +- 5) sec
(estimated error including systematics).
 
We note that our initial doubts about the reality of this burst have significantly 
diminished after analyzing the Malindi data set, but these doubts have not
been completely eliminated.  There is still a small possibility that this trigger
is a hard x-ray transient, and not a GRB.  It is, however, not at all related
to a phantom trigger due to the star tracker problem.