TITLE:   GCN CIRCULAR
NUMBER:  29691
SUBJECT: GRB 210321A: Swift-BAT refined analysis
DATE:    21/03/22 18:12:52 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), S. Dichiara (NASA/GSFC/UMCP),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), (i.e. the Swift-BAT team):

Using the data set from T-240 to T+700 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210321A (trigger #1037828)
(Dichiara, et al., GCN Circ. 29677).  The BAT ground-calculated position is
RA, Dec = 87.887, 70.109 deg which is 
  RA(J2000)  =  05h 51m 32.8s 
  Dec(J2000) = +70d 06' 33.4" 
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.

The mask-weighted light curve shows a single, fairly symmetrical peak from 
approximately T-8 to T+4 sec.  T90 (15-350 keV) is 8.21 +- 0.50 sec 
(estimated error including systematics).

The time-averaged spectrum from T-7.00 to T+1.84 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.15 +- 0.20.  The fluence in the 15-150 keV band is 6.7 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-6.99 sec in the 15-150 keV band
is 1.7 +- 0.4 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/1037828/BA/