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GCN Circular 23625

Subject
GRB 190106A: Swift-BAT refined analysis
Date
2019-01-06T21:07:30Z (5 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
T. Sakamoto (AGU), E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU),
T. N. Ukwatta (LANL)  (i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+695 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 190106A (trigger #882252)
(Sonbas, et al., GCN Circ. 23615).  The BAT ground-calculated position is
RA, Dec = 29.877, 23.839 deg, which is 
   RA(J2000)  =  01h 59m 30.6s 
   Dec(J2000) = +23d 50' 20.8" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 65%.
 
The mask-weighted light curve shows it started at ~T-10sec, with a pair of
overlapping FRED-like peaks at ~T+2 and ~T+10 sec, then a long decay and
two more peaks at ~T+57 and ~T+76 sec, and returning to baseline
at ~T+125 sec.  T90 (15-350 keV) is 76.8 +- 2.4 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-0.17 to T+99.72 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.34 +- 0.21, 
and Epeak of 120 +- 83 keV (chi squared 37.25 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.0 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+75.28 sec in the 15-150 keV band is
5.5 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.64 +- 0.05 (chi squared 43.44 for 57 d.o.f.).  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/882252/BA/
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