[vsnet-grb-info 3164] GRB 060424: Refined analysis of the Swift-BAT burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5001
SUBJECT: GRB 060424:  Refined analysis of the Swift-BAT burst
DATE:    06/04/24 15:20:49 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

D. Hullinger (BYU-Idaho), L. Barbier (GSFC), S.D. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the data set from T-240 to T+734 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060424 (trigger #206773)
(E.Rol, et al., GCN 5000).  The BAT ground-calculated position
is RA,Dec = 7.354,+36.789 deg {0h 29m 25.1s,+36d 47' 20.7"} (J2000)
+- 1.7 arcmin, (radius, sys+stat, 90% containment).  The partial coding was 53%.
 
The mask-weighted lightcurve has 5 main peaks at T-18, T-4, T+2,
T+9, and T+20 sec  with widths ranging from 4 to 8 sec FWHM.
T90 (15-350 keV) is 37 +- 2 sec (estimated error including systematics).
Swift did not automatically slew to this new burst because of the
Sun observing constraint.  It did slew to a pre-planned observing target
at T+160 sec and the new burst went out of the BAT FOV at T+240 sec. 
 
The time-averaged spectrum from T-19.6 to T+20.6 is best fit by 
a simple power-law model.  The power law index of the
time-averaged spectrum is 1.72 +- 0.19.  The fluence in the
15-150 keV band is 6.8 +- 0.8 x 10^-7 erg/cm2.  The 1-sec peak
photon flux measured from T+0.11 sec in the 15-150 keV band is
1.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.