[vsnet-grb-info 20592] GRB 180504A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22690
SUBJECT: GRB 180504A: Swift-BAT refined analysis
DATE:    18/05/05 23:31:08 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm at nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL)
(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 180504A (trigger #830822)
(Lien, et al., GCN Circ. 22682).  The BAT ground-calculated position is
RA, Dec = 331.144, -14.665 deg which is
    RA(J2000)  =  22h 04m 34.7s
    Dec(J2000) = -14d 39' 53.6"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 61%.

The mask-weighted light curve shows a triangular shaped profile, 
beginning at
~T-60 sec, peaking at ~T+20 sec, and decaying by T+80 sec.
T90 (15-350 keV) is 88.3 +- 44.4 sec (estimated error including 
systematics).

The time-averaged spectrum from T-25.03 to T+113.85 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
1.50 +- 0.13.  The fluence in the 15-150 keV band is 2.2 +- 0.2 x 
10^-6erg/cm2.
The 1-sec peak photon flux measured from T+16.80 sec in the 15-150 keV band
is 0.8 +- 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/830822/BA/