TITLE:   GCN CIRCULAR
NUMBER:  37005
SUBJECT: GRB 240730A: Swift-BAT refined analysis
DATE:    24/08/01 19:55:22 GMT
FROM:    Michael Moss at NASA GSFC <mikejmoss3@gmail.com>

D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), 
S. B. Cenko (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), 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 240730A (trigger #1245636)
(Cenko, et al., GCN Circ. 36976).  The BAT ground-calculated position is
RA, Dec = 37.841, 59.045 deg which is 
   RA(J2000)  =  02h 31m 21.9s 
   Dec(J2000) = +59d 02' 43.5" 
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.
 
The BAT mask-weighted light curve displays two spectrally soft peaks.  
The T90 (15-350 keV) is 50.13 +- 7.60 sec (estimated error including systematics).
 
The time-averaged spectrum from T-6.06 to T+53.43 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.50 +- 0.19.  The fluence in the 15-150 keV band is 6.8 +- 0.9 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+5.80 sec in the 15-150 keV band
is 0.4 +- 0.1 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/1245636

The long duration and proximity to the Galactic plane raised the initial 
possibility that this was a Galactic transient.  However, its subsequent behavior, 
including a lack of later BAT detections, is consistent with a GRB, making the 
Galactic transient interpretation less likely.