TITLE:   GCN CIRCULAR
NUMBER:  35472
SUBJECT: GRB 240101B: Swift-BAT refined analysis
DATE:    24/01/03 14:03:29 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  S. B. Cenko (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
M. J. Moss (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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 240101B (trigger #1205744)
(Cenko, et al., GCN Circ. 35449).  The BAT ground-calculated position is
RA, Dec = 352.147, 51.646 deg which is
   RA(J2000)  =  23h 28m 35.3s
   Dec(J2000) = +51d 38' 46.9"
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a single peak from approximately T+0
To T+18 seconds.  There is a possible precursor at T-50 sec.

T90 (15-350 keV) is 43.1 +- 12.6 sec (estimated error including systematics).
The time-averaged spectrum from T+2.18 to T+48.32 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.70 +- 0.26.  The fluence in the 15-150 keV band is 4.6 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+10.28 sec in the 15-150 keV band
is 0.5 +- 0.1 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/1205744/BA/