GRB 240421***A***, Swift-BAT refined analysis
 
<somebody goes first>
<add the BA alphabetically>
S. D. Barthelmy (GSFC), 
R. Gupta (GSFC),
H. A. Krimm (NSF),
S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC),
M. J. Moss (GSFC),
D. M. Palmer (LANL),
T. Parsotan (GSFC),
D. Sadaula (GSFC/UMBC),
T. Sakamoto (AGU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240421***A*** (trigger #1223470)
(NAME, et al., GCN Circ. xxxx).  The BAT ground-calculated position is
RA, Dec = 299.687, -14.869 deg which is 
   RA(J2000)  =  19h 58m 45.0s 
   Dec(J2000) = -14d 52' 07.4" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.
 
[Description about the mask-weighted light curve]
T90 (15-350 keV) is 12.4 +- 2.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-7.1 to T+8.0 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.37 +- 0.50, 
and Epeak of 76.8 +- 13.0 keV (chi squared 57.22 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 5.3 +- 0.4 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV band is
19.4 +- 1.8 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.54 +- 0.10 (chi squared 77.64 for 57 d.o.f.).  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/1223470/BA/