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GCN Circular 27519

Subject

GRB 200409A: Swift-BAT refined analysis

Date

2020-04-10T03:56:27Z (4 years ago)

From

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

S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF), J.D. Gropp (PSU),
S. Laha (GSFC/UMBC), 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-240 to T+963 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 200409A (trigger #965484)
(Gropp et al., GCN Circ. 27509Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 60.555, -50.243 deg which is
   RA(J2000)  =  04h 02m 13.3s
   Dec(J2000) = -50d 14' 36.4"
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.

The mask-weighted light curve shows several overlapping pulses that start
at ~T0 and ends at~T+19 s. The main peak occurs at ~T0. T90 (15-350 keV)
is 17.91 +- 5.20 sec (estimated error including systematics).

The time-averaged spectrum from T+0.01 to T+19.01 sec is best fit by a
simple
power-law model.  The power law index of the time-averaged spectrum is
2.14 +- 0.44.  The fluence in the 15-150 keV band is 2.3 +- 0.6 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+0.01 sec in the 15-150 keV band
is 1.2 +- 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/965484/BA/