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GCN Circular 18048

Subject

GRB 150722A: Swift-BAT refined analysis

Date

2015-07-22T23:51:39Z (9 years ago)

From

Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
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-240 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150722A (trigger #649916)
(Marshall, et al., GCN Circ. 18042Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 218.297, -35.196 deg which is
    RA(J2000)  =  14h 33m 11.3s
    Dec(J2000) = -35d 11' 45.1"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.

The mask-weighted light curve shows weak, variable emission from prior to T-200
to about T+55 seconds.  T90 (15-350 keV) is 67 +- 12 sec (estimated error
including systematics).

The time-averaged spectrum from T-26.00 to T+48.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.26.  The fluence in the 15-150 keV band is 6.1 +- 0.9 x 10^-07  erg/cm2.
The 1-sec peak photon flux measured from T+15.00 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
http://gcn.gsfc.nasa.gov/notices_s/649916/BA/

[GCN OPS NOTE(22jul15): Per an author's request, the "T-60" was corrected
to "T-240".]