GRB070731: Summary Image Light curves Spectra Distribution Others

Analysis Summary

Notes:

• 1) No attempt has been made to eliminate the non-significant decimal places.
• 2) This batgrbproduct analysis is done using the HEASARC data.
• 3) This batgrbproduct analysis is using the flight position for the mask-weighting calculation.

======================================================================
                  BAT GRB EVENT DATA PROCESSING REPORT
    Process Script Ver: batgrbproduct v2.46
    Process Start Time: Mon Jan 20 08:08:01 EST 2014
             Host Name: batevent1
   Current Working Dir: /local/data/batevent/batevent_reproc/trigger286574
======================================================================

  Trigger: 00286574      Segment: 000

  BAT Trigger Time: 207567204.8   [s; MET]
      Trigger Stop: 207567205.312   [s; MET]
               UTC: 2007-07-31T09:33:22.676340    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 328.569634421567   Dec: -15.7454090771216  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    7.54
     Image Trigger?:     NO
     Rate S/N Ratio:     13.7840487520902  [ if not an image trigger ]
     Image S/N Ratio:    7.54

  Analysis Position:   [ source = BAT ]
    RA: 328.569634421567   Dec: -15.7454090771216  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 328.584430515266   Dec: -15.7429950018337  [deg; J2000]  
        { 21h 54m 20.3s , -15d 44' 34.8" }
         +/- 1.92440188423991 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.648632981520966 [arcmin] (formal 1-sigma fit error)
    SNR: 11.9393741127866
 
  Angular difference between the analysis and refined position is 0.866649 arcmin
 
  Partial Coding Fraction: 0.4921875    [ including projection effects ]

  Duration
     T90: 2.85600000619888 +/- 0.38907581688944
        Measured from: -0.0560000240802765
                   to: 2.79999998211861     [s; relative to TRIGTIME]
     T50: 1.81600001454353 +/- 0.622356818612982
        Measured from: 0.227999985218048
                   to: 2.04399999976158     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: -0.144000023603439     
                   to: 0.855999976396561     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -0.144000023603439     
                   to: 2.9839999973774     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.080882   0.110805   0.072328   0.017615
           0.012204   0.013091   0.011708   0.009720 [error]
 Peak      0.039478   0.052529   0.045829   0.013128
           0.007111   0.007682   0.007249   0.005743 [error]

     [ fluence units of on-axis counts / fully illuminated detector ] 

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100    3.128   -0.144    2.984
T90     2.856   -0.056    2.800
T50     1.816    0.228    2.044
Peak    1.000   -0.144    0.856
 
 
====== Spectral Analysis Summary =====================================
 
Model      : spectral model: simple power-law (PL) and cutoff power-law (CPL)
Ph_index   : photon index: E^{Ph_index}
Ph_90err   : 90% error of the photon index
Epeak      : Epeak in keV
Epeak_90err: 90% error of Epeak
Norm       : normalization at 50 keV in both the PL model and CPL model
Nomr_90err : 90% error of the normalization
chi2       : Chi-Squared
dof        : degree of freedo
 
=== Time-averaged spectral analysis ===
(Best model with acceptable fit: PL)
 
Model Ph_index Ph_90err_low Ph_90err_hi  Epeak  Epeak_90err_low  Epeak_90err_hi  Norm       Nomr_90err_low    Norm_90err_hi    chi2    dof
PL      -1.584    -0.229      0.222       -           -               -         5.69e-03     -8.35e-04          8.23e-04      48.440   57
CPL     -0.554    -1.021      1.252       64.332     -15.717       171.089      2.06e-02     -2.06e-02          7.69e-02      44.980   56
 
 
=== 1-s peak spectral analysis ===
(Best model with acceptable fit: PL)
 
Model Ph_index Ph_90err_low Ph_90err_hi  Epeak  Epeak_90err_low  Epeak_90err_hi  Norm       Nomr_90err_low    Norm_90err_hi    chi2    dof
PL      -1.327     -0.251     0.249       -           -               -         9.88e-03     -1.51e-03          1.51e-03      49.250   57
CPL     -0.536     -0.895     1.241       95.844     -32.620       -95.844      2.42e-02     -1.51e-02          6.90e-02      47.300   56
 
 
=== Fluence/Peak Flux Summary ===
 
              Model    Band1     Band2     Band3     Band4     Band5     Total
                       15-25     25-50    50-100    100-350    15-150    15-350    keV
Fluence         PL   2.46e-08  4.29e-08  5.73e-08  1.56e-07  1.67e-07  2.81e-07   erg/cm2
      90%_error_low -4.92e-09 -5.84e-09 -1.09e-08 -5.31e-08 -2.62e-08 -6.49e-08   erg/cm2
      90%_error_hi   5.12e-09  5.82e-09  1.10e-08  6.84e-08  2.67e-08  7.73e-08   erg/cm2
Peak flux       PL   3.44e-01  3.84e-01  3.06e-01  4.05e-01  1.18e+00  1.44e+00   ph/cm2/s
      90%_error_low -8.55e-02 -6.30e-02 -5.72e-02 -1.35e-01 -1.80e-01 -2.27e-01   ph/cm2/s
      90%_error_hi   9.17e-02  6.22e-02  5.65e-02  1.69e-01  1.80e-01  2.32e-01   ph/cm2/s
 
Fluence        CPL   2.18e-08  4.85e-08  5.84e-08  3.83e-08  1.53e-07  1.67e-07   erg/cm2
      90%_error_low -5.78e-09 -7.84e-09 -1.31e-08 -2.76e-08 -2.80e-08 -3.96e-08   erg/cm2
      90%_error_hi   5.83e-09  8.30e-09  1.27e-08  9.91e-08  2.95e-08  9.97e-08   erg/cm2
Peak flux      CPL   2.96e-01  4.12e-01  3.30e-01  1.88e-01  1.15e+00  1.23e+00   ph/cm2/s
      90%_error_low -1.04e-01 -7.32e-02 -6.62e-02 -1.16e-01 -1.85e-01 -2.27e-01   ph/cm2/s
      90%_error_hi   1.09e-01  7.66e-02  6.89e-02  2.79e-01  1.84e-01  3.34e-01   ph/cm2/s
 
======================================================================

Image

Pre-slew 15.0-350.0 keV image (Event data)

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  328.5844   -15.7430   0.0162    26.3413   107.6686         0.2899573     11.939 TRIG_00286574                 
 
Foreground time interval of the image:
 -0.144   2.984 (delta_t =   3.128 [sec])
Background time interval of the image:
-239.800  -0.144 (delta_t = 239.656 [sec])

Light Curves

Note: The mask-weighted lightcurves have units of either count/det or counts/sec/det, where a det is 0.4 x 0.4 = 0.16 sq cm.

Full-time range; 1 s binning

Other quick-look light curves:

• 64 ms binning (zoomed)
• 16 ms binning (zoomed)
• 8 ms binning (zoomed)
• 2 ms binning (zoomed)
• SN=5 or 10 s binning (full-time range)
• Raw light curve

Spectra

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   -0.144 sec. to    2.984 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.58412     ( -0.228665   0.221664 )
Norm@50keV  : 5.68834E-03    ( -0.000834614   0.00082301 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          48.44 using 59 PHA bins.
# Reduced chi-squared =         0.8498 for     57 degrees of freedom 
# Null hypothesis probability =   7.830204e-01
 
Photon flux (15-150 keV)    in 3.128 sec: 0.727454 ( -0.098314  0.098348 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.66754e-07 ( -2.6183e-08  2.66636e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.144 sec. to    2.984 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.553655     ( -1.02092   1.25179 )
Epeak [keV] : 64.3323      ( -15.7167 171.089 )
Norm@50keV  : 2.05906E-02    ( -0.0205906   0.0768661 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          44.98 using 59 PHA bins.
# Reduced chi-squared =         0.8032 for     56 degrees of freedom 
# Null hypothesis probability =   8.542628e-01
 
Photon flux (15-150 keV)    in 3.128 sec: 0.703530 ( -0.101051  0.100964 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.5284e-07 ( -2.80279e-08  2.94768e-08 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   -0.144 sec. to    0.856 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.32702     ( -0.250907   0.248783 )
Norm@50keV  : 9.87735E-03    ( -0.00151206   0.00150582 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          49.25 using 59 PHA bins.
# Reduced chi-squared =         0.8640 for     57 degrees of freedom 
# Null hypothesis probability =   7.576875e-01
 
Photon flux (15-150 keV)    in 1 sec: 1.18448 ( -0.17993  0.18009 ) ph/cm2/s
Energy fluence (15-150 keV)             : 9.69907e-08 ( -1.6577e-08  1.68035e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.144 sec. to    0.856 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.535738     ( -0.894744   1.24068 )
Epeak [keV] : 95.8438      ( -32.6196 -95.8433 )
Norm@50keV  : 2.42451E-02    ( -0.0151384   0.0689704 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          47.30 using 59 PHA bins.
# Reduced chi-squared =         0.8447 for     56 degrees of freedom 
# Null hypothesis probability =   7.894786e-01
 
Photon flux (15-150 keV)    in 1 sec: 1.15331 ( -0.18494  0.18449 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.9819e-08 ( -1.84379e-08  1.47819e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 2.856 sec.
Hardness ratio (energy fluence ratio) = 1.33410535322

S(15-50 keV) vs. S(50-150 keV) plot

S(15-50 keV)  = 6.750592e-08
S(50-150 keV) = 9.924781e-08

The dash-dotted line and the dashed line traces the fluences calculated from the Band function with Epeak = 15 and 150 keV, respectively. Both lines assume a canonical values of alpha = -1 and beta = -2.5.

Mask shadow pattern

IMX = -1.502765794764963E-01, IMY = -4.717709638029596E-01

Spacecraft aspect plot

Bright source in the pre-burst/pre-slew/post-slew images

Pre-burst image of 15-350 keV band

Time interval of the image:
-239.800000 -0.144000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
264.5831 -44.3262    6.9  50.7    4.8  -0.7179  -1.7   10.1	4U 1735-44                    
275.9221 -30.3658  247.3  48.8   26.5   0.0278   0.0    0.2	H1820-303                     
284.9196 -24.9767    5.0  45.0   38.5   1.1140   2.3    7.2	HT1900.1-2455                 
314.6236  -9.9910    2.7  36.5   86.8   1.8460   4.3 ------	UNKNOWN                       
292.2061 -54.0524    2.9  31.4   -5.3   0.7201   3.9 ------	UNKNOWN                       
257.4767 -71.4587    2.3  47.6  -31.4   1.7165   5.1 ------	UNKNOWN                       
 39.1483 -37.4608    2.3  48.0 -129.0   3.8366   5.0 ------	UNKNOWN                       

Pre-slew background subtracted image of 15-350 keV band

Time interval of the image:
-0.144000 2.984000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
264.7929 -44.3729    4.3  50.5    4.8  -0.1198  -2.7    5.1	4U 1735-44                    
275.8684 -30.3730    7.0  48.9   26.4   0.1090   1.7    2.9	H1820-303                     
285.1607 -24.9237    4.6  44.8   38.8   0.1349   2.5    6.8	HT1900.1-2455                 
328.5844 -15.7430    1.0  26.3  107.7   0.2899  11.9 ------	UNKNOWN                       
 13.2053   0.9002    2.6  54.1  172.1   0.2947   4.4 ------	UNKNOWN                       
  7.3848  -9.7626    2.9  42.0  174.0   0.1030   3.9 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
917.500600 962.285300
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
357.3924  14.1044    2.2  52.9  157.5   1.5658   5.3 ------	UNKNOWN                       
 14.1628  12.7459    2.7  55.5  177.5   1.0653   4.3 ------	UNKNOWN                       
257.6414 -85.1682    2.6  52.0  -23.7   0.7157   4.5 ------	UNKNOWN                       
 39.7542  -7.6745    2.8  53.2 -142.2   1.2799   4.1 ------	UNKNOWN