TITLE:   GCN CIRCULAR
NUMBER:  33363
SUBJECT: GRB 230217A: Swift-BAT refined analysis
DATE:    23/02/21 18:54:55 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GWU),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230217A (trigger #1154967)
(Moss, et al., GCN Circ. 33339).  The BAT ground-calculated position is
RA, Dec = 280.759, -28.840 deg which is
   RA(J2000)  =  18h 43m 02.2s
   Dec(J2000) = -28d 50' 23.0"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 21%.

The mask-weighted light curve shows a double-peaked event running from
T -0.2 sec to about T+1.2 sec. T90 (15-350 keV) is 1.30 +- 0.45 sec.
(estimated error including systematics).  The T90 vs. hardness diagram shows
the burst well within the short-hard burst region.

The time-averaged spectrum from T-0.26 to T+1.75 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.99 +- 0.12.  The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.24 sec in the 15-150 keV band
is 20.2 +- 1.5 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1154967/BA/