[vsnet-grb-info 2749] GRB 060124: Extremely long burst, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4586
SUBJECT: GRB 060124: Extremely long burst, Swift-BAT refined analysis
DATE:    06/01/25 01:02:04 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

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

Using the data set from T-50.0 to T+1000.0 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060124 (trigger #178750) 
(Holland, et al., GCN 4570).  The BAT ground-calculated position is 
(RA,Dec) = 77.128, 69.724  deg {5h 8m 30.6s, 69d 43' 27.9"} (J2000)
+- 1.6 arcmin, (radius, sys+stat, 90% containment).  The partial coding 
was 62%.

The BAT mask-weighted lightcurve has a precursor from T-3 to T+13 sec, 
then three major peaks: T+520 to T+550 sec, T+560 to T+580 sec (with the 
largest flux), and T+690 to T+710 sec. Thus the total duration is one of 
the longest recorded by BATSE or Swift. 
 
The spectrum of the main peaks appears slightly harder than the precursor, 
but so far we have detailed data for the precursor only.  The spectrum of 
the precursor from T-1.2 to T+13.2 is best fit by a simple power-law model 
with a photon index of 1.89 +- 0.19.  The fluence of the precursor emission 
in the 15-150 keV band is (4.6 +- 0.5) x 10^-07 erg/cm2. The peak flux in 
the 15-150 keV band was about 4.5 +- 0.5 counts/cm2/sec at T+570.  

We have made a preliminary estimate of the total fluence in the BAT
energy range for this burst by scaling the fluence of the precursor 
by the mask-weighted counts ratio between the entire burst and the 
precursor.  This estimated total fluence is ~7 x 10^-6 erg/cm2 in the 
15-150 keV band.