Notes:
- 1) The fitting includes the systematic errors.
- 2) When the burst includes telescope slew time periods, the fitting uses an average response file made from multiple 5-s response files through out the slew time plus single time preiod for the non-slew times, and weighted by the total counts in the corresponding time period using addrmf. An average response file is needed becuase a spectral fit using the pre-slew DRM will introduce some errors in both a spectral shape and a normalization if the PHA file contains a lot of the slew/post-slew time interval.
- 3) For fits to more complicated models (e.g. a power-law over a cutoff power-law), the BAT team has decided to require a chi-square improvement of more than 6 for each extra dof.
Time averaged spectrum fit using the average DRM
Power-law model
Time interval is from -10.280 sec. to 10.040 sec.
Spectral model in power-law:
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Parameters : value lower 90% higher 90%
Photon index: -1.75039 ( -0.262697 0.255014 )
Norm@50keV : 4.08684E-03 ( -0.000757801 0.000752675 )
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#Fit statistic : Chi-Squared = 98.46 using 59 PHA bins.
# Reduced chi-squared = 1.727 for 57 degrees of freedom
# Null hypothesis probability = 5.385711e-04
Photon flux (15-150 keV) in 20.32 sec: 0.552855 ( -0.099733 0.100279 ) ph/cm2/s
Energy fluence (15-150 keV) : 7.66009e-07 ( -1.4409e-07 1.45947e-07 ) ergs/cm2
Cutoff power-law model
Time interval is from -10.280 sec. to 10.040 sec.
Spectral model in the cutoff power-law:
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Parameters : value lower 90% higher 90%
Photon index: 1.07809 ( -1.32236 1.74234 )
Epeak [keV] : 51.9235 ( -7.99516 10.608 )
Norm@50keV : 0.118951 ( -0.116804 0.780766 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 81.83 using 59 PHA bins.
# Reduced chi-squared = 1.461 for 56 degrees of freedom
# Null hypothesis probability = 1.379570e-02
Photon flux (15-150 keV) in 20.32 sec: 0.513571 ( -0.095077 0.099208 ) ph/cm2/s
Energy fluence (15-150 keV) : 6.94391e-07 ( -1.32343e-07 1.38414e-07 ) ergs/cm2
1-s peak spectrum fit
Power-law model
Time interval is from 1.596 sec. to 2.596 sec.
Spectral model in power-law:
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Parameters : value lower 90% higher 90%
Photon index: -1.49095 ( -0.387964 0.37959 )
Norm@50keV : 1.39527E-02 ( -0.00352466 0.00351967 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 57.03 using 59 PHA bins.
# Reduced chi-squared = 1.000 for 57 degrees of freedom
# Null hypothesis probability = 4.740418e-01
Photon flux (15-150 keV) in 1 sec: 1.73779 ( -0.4547 0.45935 ) ph/cm2/s
Energy fluence (15-150 keV) : 1.32568e-07 ( -3.4923e-08 3.52738e-08 ) ergs/cm2
Cutoff power-law model
Time interval is from 1.596 sec. to 2.596 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters : value lower 90% higher 90%
Photon index: 0.632816 ( -1.82815 3.09968 )
Epeak [keV] : 65.8506 ( -16.7231 77.942 )
Norm@50keV : 0.142605 ( -0.142559 3.88574 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 52.86 using 59 PHA bins.
# Reduced chi-squared = 0.9439 for 56 degrees of freedom
# Null hypothesis probability = 5.944558e-01
Photon flux (15-150 keV) in 1 sec: 1.61919 ( -0.45155 0.46599 ) ph/cm2/s
Energy fluence (15-150 keV) : 1.23643e-07 ( -3.56739e-08 3.69845e-08 ) ergs/cm2
Time-resolved spectra
