GCN Circular 25579
Subject
GRB 190829A, Swift-BAT refined analysis
Date
2019-08-30T15:10:52Z (5 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), S. Dichiara (NASA/GSFC/UMCP),
H. A. Krimm (NSF), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
(i.e. the Swift-BAT team):(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 190829A (trigger #922968)
(Dichiara, et al., GCN Circ. 25552). The BAT ground-calculated position is
RA, Dec = 44.542, -8.958 deg which is
RA(J2000) = 02h 58m 10.0s
Dec(J2000) = -08d 57' 28.4"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 5%.
The mask-weighted light curve shows an early peak centered at T-50 sec, coincident
with the Fermi/GBM trigger (Lesage, et al., GCN Circ. 25575). This early peak
shows more counts in the higher energy bands (> 50 keV) than is typical for a precursor.
This was followed by the main peak of emission from T-5 to T+10 sec, peaking at the
trigger time. Finally, there was a weak, hard peak between T+15 and T+20 sec.
T90 (15-350 keV) is 58.2 +- 8.9 sec (estimated error including systematics).
The time-averaged spectrum from T-51.9 to T+7.2 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.56 +- 0.21. The fluence in the 15-150 keV band is 6.4 +- 0.7 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band
is 18.0 +- 2.7 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/922968/BA/