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GCN Circular 30368

Subject
GRB 210702A, Swift-BAT refined analysis
Date
2021-07-04T20:12:21Z (3 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), 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+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210702A (trigger #1058804)
(Lien et al., GCN Circ. 30351).  The BAT ground-calculated position is
RA, Dec = 168.570, -36.741 deg which is
   RA(J2000)  =  11h 14m 16.8s
   Dec(J2000) = -36d -44' -29.2"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.

The mask-weighted light curve shows a single-peaked FRED-like structure
that starts at ~T-4 s, peaks at ~T+1 s, and ends at ~T+370 s. The burst
went out of the BAT field of view at T+452 s. There might be addition
burst emission afterwards. T90 (15-350 keV) is 138.2 +- 47.6 sec
(estimated error including systematics).

The burst occurred at a location with a very low partial coding fraction,
and thus was out of the BAT calibrated field of view until ~T+18 s.
Therefore, the spectral analysis is only available for the burst duration
afterwards. The time-averaged spectrum from T+18.0 to T+369.2 sec is
best fit by a simple power-law model.  The power law index of the
time-averaged spectrum is 1.54 +- 0.09.  The fluence in the 15-150 keV
band is 9.8 +- 0.5 x 10^-6 erg/cm2. 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/1058804/BA/
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