[vsnet-grb-info 9530] GRB 100727A, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11001
SUBJECT: GRB 100727A, Swift-BAT refined analysis
DATE:    10/07/27 14:00:16 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. C. Morris (GWU/GSFC), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), J. Tueller (GSFC),
T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+617 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100727A (trigger #430094)
(Morris, et al., GCN Circ. 10998).  The BAT ground-calculated position is
RA, Dec = 154.187, -21.417 deg which is
    RA(J2000)  =  10h 16m 44.8s
    Dec(J2000) = -21d 25' 02.7"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.

The burst began with weak precursor activity starting at T-80 sec
and peaking at T-40 sec.  The main pulse, a mostly featureless
FRED profile, began at T-2 sec and continued to approximately
T+50 sec. T90 (15-350 keV) is 84 +- 14 sec (estimated error
including systematics).

The time-averaged spectrum from T-82.0 to T+29.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.81 +- 0.13.  The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.33 sec in the 15-150 keV band
is 1.2 +- 0.1 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/430094/BA/