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GCN Circular 7531

Subject

GRB 080325, Swift-BAT refined analysis

Date

2008-03-28T18:08:58Z (17 years ago)

From

Craig Markwardt at NASA/GSFC/UMD <craigm@milkyway.gsfc.nasa.gov>

E. Fenimore (LANL), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU), (i.e. the Swift-BAT team), and
L. Vetere (PSU):

Using the data set from T-323 to T+963 sec from all of the telemetry,
we report further analysis of BAT GRB 080325 (trigger #307604)
(Vetere, et al., GCN Circ. 7512Not found
 
 
).  The BAT ground-calculated position
is RA, Dec = 277.906, 36.516 deg which is
    RA(J2000)  =  18h 31m 37.5s
    Dec(J2000) = +36d 30' 57.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 10%.

The mask weighted light curve has a broad FRED-like structure, with
a rise to peak within ~20 sec, followed by a gradual decay extending
out to T+200 sec. The low partial coding in the initial part of the
burst makes it difficult to distinguish between statistical and real
fluctuations.  T90 (15-350 keV) is 128.4 +- 34.2 sec (estimated
error including systematics).

The time-averaged spectrum from T-29.3 to T+170.5 sec is best fit by a
simple power-law model.  The power law index of the time-averaged
spectrum is 1.68 +- 0.17.  The fluence in the 15-150 keV band is
4.9 +- 0.4 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from
T+38.02 sec in the 15-150 keV band is 1.4 +- 0.6 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/307604/BA/