GCN Circular 4822
Subject
GRB 060218/SN 2006aj: Swift-BAT fluence and peak flux
Date
2006-02-23T21:19:22Z (18 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), J. Tueller (GSFC),
on behalf of the Swift-BAT team:
We report further analysis of BAT GRB 060218/SN 2006aj (trigger #191157)
(Cusumano, et al., GCN 4775, Barbier, et al., GCN 4780,
Nousek, et al., GCN 4805).
The time-averaged spectrum from T-8 to T+2732 is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 2.5 +- 0.1. The fluence in the 15-150 keV band is
6.8 +- 0.4 x 10^-6 erg/cm2. The peak energy flux in 1.6 sec time
interval starting from T+455.2 sec in the 15-150 keV band is
2.0 +- 1.1 x 10^-8 erg/cm2/sec.
Using the redshift of z=0.033 (Soderberg, et al., GCN 4804), the
isotropic equivalent energy, Eiso, is 1.9 +- 0.1 x 10^49 erg,
and the peak luminosity, Liso, is 6 +- 3 x 10^46 erg/s in
15.5 keV - 154.8 keV at the GRB rest frame. This Eiso is
comparable to that of the one of the softest X-ray flash XRF 020903
observed by HETE-2 (Sakamoto et al., ApJ, 602, 875, Soderberg et al.,
ApJ, 606, 994). The Liso is comparable to that of GRB 980425/SN 1998bw
(Galama et al., Nature, 395, 670). Note that the BAT Eiso and Liso
of GRB 060218 are not bolometric values due to its narrow energy band.
All the quoted errors are at the 90% confidence level. We use
Omega_M = 0.3, Omega_lamda = 0.7, and H0 = 65 in the calculation
of the luminosity distance.