Back
GCN Circular 17491

Subject
GRB 150222A: Swift-BAT refined analysis
Date
2015-02-23T01:16:22Z (10 years ago)
From
Hans Krimm at NASA-GSFC <hans.a.krimm@nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
M. G. Bernardini (INAF-OAB), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-60 to T+117 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150222A (trigger #632180)
(Bernardini, et al., GCN Circ. 17486Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 198.787, -12.151 deg which is
    RA(J2000)  =  13h 15m 09.0s
    Dec(J2000) = -12d 09' 02.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.

The mask-weighted light curve shows a double-peaked structure, with a first peak 
from T+0 to T+3 sec and a second, larger peak from T+3 to T+18 sec, followed by 
lower level emission out to ~T+40 sec.
T90 (15-350 keV) is 15.90 +- 7.32 sec (estimated error including systematics).

The time-averaged spectrum from T-0.14 to T+28.11 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.08.  The fluence in the 15-150 keV band is 2.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+5.62 sec in the 15-150 keV band
is 4.7 +- 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/632180/BA/