TITLE:   GCN CIRCULAR
NUMBER:  36072
SUBJECT: GRB 240411B: Swift-BAT refined analysis
DATE:    24/04/12 17:35:46 GMT
FROM:    Mike Moss at NASA GSFC <mikejmoss3@gmail.com>

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), 
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), M. J. Moss (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC),
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 240411B (trigger #1221183)
(Parsotan, et al., GCN Circ. 36063).  The BAT ground-calculated position is
RA, Dec = 231.562, -2.172 deg which is 
   RA(J2000)  =  15h 26m 14.8s 
   Dec(J2000) = -02d 10' 20.9" 
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.
 
The mask-weighted light curve shows two spikes separated by an interval of ~15 seconds. 
The estimated T90 (15-350 keV) is 33.26 +- 1.49 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.37 to T+33.92 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.69 +- 0.41.  The fluence in the 15-150 keV band is 4.9 +- 1.2 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+32.87 sec in the 15-150 keV band
is 0.9 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1221183