[vsnet-grb-info 13517] GRB 130608A: Further Swift-BAT analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14850
SUBJECT: GRB 130608A: Further Swift-BAT analysis
DATE:    13/06/10 14:16:12 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

H. A. Krimm (GSFC/USRA)for the Swift-BAT team:

Using the full data set from T-239 to T+963 sec,we report further
analysis of BAT GRB 130608A (trigger #557771)(Krimm, et al.,
GCN Circ. 14827; Krimm, et al., GCN Circ. 14833). Information in
this Circular supersedes that presented in Krimm, et al., GCN Circ. 14833.

The BAT ground-calculated position isrefined to RA, Dec = 24.597,
41.492 deg which is
    RA(J2000)  =  01h 38m 23.3s
    Dec(J2000) = +41d 29' 30.5"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 45%.

The initial Swift-BAT circular reported a broad peak starting at
~T-25 sec, peaking at ~T+5 sec, and ending at ~T+50 sec. With further
data available we see that the mask-weighted light curve contains
precursor emission from~T-150 sec to ~T-90. BAT did not trigger on
this precursor because it occurred during a slew to the field containing
the burst.  T90 (15-350 keV) is 151.38 +- 10.84 sec (estimated error
including systematics).

The time-averaged spectrum from T-134.19 to T+22.20 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.71 +- 0.41.  The fluence in the 15-150 keV band is 9.0 +- 1.9 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+19.06 sec in the 15-150 keV band
is 0.6 +- 0.3 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/557771/BA/