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GCN Circular 22229

Subject

GRB 171209A: Swift-BAT refined analysis

Date

2017-12-10T17:50:20Z (7 years ago)

From

Amy Lien at GSFC <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
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-239 to T+400 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171209A (trigger #796100)
(LaPorte et al., GCN Circ. 22213Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 139.387, -30.523 deg which is
  RA(J2000)  =  09h 17m 32.8s
  Dec(J2000) = -30d 31' 22.4"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 61%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-70 s and ends at ~ T+230 s. T90 (15-350 keV) is 161.7 +- 30.8 sec (estimated
error including systematics).

The time-averaged spectrum from T-70.76 to T+228.44 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.58 +- 0.07.  The fluence in the 15-150 keV band is 7.5 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+79.52 sec in the 15-150 keV band
is 1.6 +- 0.2 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/796100/BA/