TITLE:   GCN CIRCULAR
NUMBER:  31834
SUBJECT: GRB 220403B: Swift-BAT refined analysis
DATE:    22/04/05 13:29:33 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII)
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), 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 220403B (trigger #1101053)
(Klingler, et al., GCN Circ. 31820).  The BAT ground-calculated position is
RA, Dec = 190.974, 89.180 deg which is
    RA(J2000)  =  12h 43m 53.9s
    Dec(J2000) = +89d 10' 49.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.

The mask-weighted light curve shows a bright peak structure that starts
at T-19 s, peaks at T-1 s and ends at T+40 s.  T90 (15-350 keV) is
27.0 +- 3.4 sec (estimated error including systematics).
  
The time-averaged spectrum from T-14.42 to T+27.96 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.06.  The fluence in the 15-150 keV band is 3.7 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.06 sec in the 15-150 keV band
is 2.7 +- 0.3 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/1101053/BA/