GRB130831B: 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: Sat Jan 11 23:28:01 EST 2014
             Host Name: batevent1
   Current Working Dir: /local/data/batevent/batevent_reproc/trigger568855
======================================================================

  Trigger: 00568855      Segment: 000

  BAT Trigger Time: 399649710.656   [s; MET]
      Trigger Stop: 399649712.704   [s; MET]
               UTC: 2013-08-31T13:48:19.679500    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 192.445770104134   Dec: -29.176729615974  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    7.44
     Image Trigger?:     NO
     Rate S/N Ratio:     10.6301458127346  [ if not an image trigger ]
     Image S/N Ratio:    7.44

  Analysis Position:   [ source = BAT ]
    RA: 192.445770104134   Dec: -29.176729615974  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 192.448266410614   Dec: -29.1860594174343  [deg; J2000]  
        { 12h 49m 47.6s , -29d 11' 09.8" }
         +/- 2.05772164941592 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.725518288065002 [arcmin] (formal 1-sigma fit error)
    SNR: 10.8498366270971
 
  Angular difference between the analysis and refined position is 0.574859 arcmin
 
  Partial Coding Fraction: 0.1484375    [ including projection effects ]

  Duration
     T90: 37.5840000510216 +/- 9.54610205001519
        Measured from: -11.3360000252724
                   to: 26.2480000257492     [s; relative to TRIGTIME]
     T50: 7.82400006055832 +/- 9.28046892973469
        Measured from: -2.87200003862381
                   to: 4.95200002193451     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: -0.0520000457763672     
                   to: 0.947999954223633     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -13.9120000004768     
                   to: 30.5519999861717     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.575255   0.998312   0.507385   0.082319
           0.091787   0.094623   0.083553   0.070660 [error]
 Peak      0.072194   0.108116   0.065344   0.035184
           0.015130   0.016003   0.015333   0.012188 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   44.464  -13.912   30.552
T90    37.584  -11.336   26.248
T50     7.824   -2.872    4.952
Peak    1.000   -0.052    0.948
 
 
====== 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      -1.754    -0.207      0.201       -           -               -         3.55e-03     -4.69e-04          4.64e-04      37.890   57
CPL     -0.242    -1.097      1.524       53.050      -9.366        26.069      2.32e-02     -2.32e-02          1.32e-01      31.870   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      -1.655     -0.342     0.328       -           -               -         1.84e-02     -3.61e-03          3.53e-03      53.310   57
CPL     -1.659     -0.338     0.336     9999.290    -9999.280      -9999.290      1.84e-02     -3.57e-03          5.39e-02      53.310   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   2.56e-07  4.03e-07  4.78e-07  1.10e-06  1.46e-06  2.24e-06   erg/cm2
      90%_error_low -4.81e-08 -5.10e-08 -8.09e-08 -3.36e-07 -1.96e-07 -4.24e-07   erg/cm2
      90%_error_hi   5.03e-08  5.08e-08  8.09e-08  4.18e-07  1.98e-07  4.83e-07   erg/cm2
Peak flux       PL   8.80e-01  8.08e-01  5.13e-01  5.00e-01  2.41e+00  2.70e+00   ph/cm2/s
      90%_error_low -2.63e-01 -1.57e-01 -1.29e-01 -2.15e-01 -4.53e-01 -4.96e-01   ph/cm2/s
      90%_error_hi   2.85e-01  1.54e-01  1.26e-01  2.93e-01  4.55e-01  4.97e-01   ph/cm2/s
 
Fluence        CPL   2.10e-07  4.74e-07  4.85e-07  1.85e-07  1.31e-06  1.35e-06   erg/cm2
      90%_error_low -5.85e-08 -7.22e-08 -1.09e-07 -1.37e-07 -2.15e-07 -2.53e-07   erg/cm2
      90%_error_hi   5.98e-08  7.65e-08  9.96e-08  4.25e-07  2.25e-07  4.49e-07   erg/cm2
Peak flux      CPL   8.95e-01  8.01e-01  5.09e-01  4.99e-01  2.42e+00  2.71e+00   ph/cm2/s
      90%_error_low     N/A   -1.54e-01 -1.23e-01     N/A   -6.99e-01 -5.06e-01   ph/cm2/s
      90%_error_hi      N/A    1.72e-01  1.33e-01     N/A    4.63e-01  4.81e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  192.4483   -29.1861   0.0178    49.8577  -144.6222         2.0730358     10.850 TRIG_00568855                 
 
Foreground time interval of the image:
-13.912  26.845 (delta_t =  40.757 [sec])
Background time interval of the image:
-239.656 -13.912 (delta_t = 225.744 [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  -13.912 sec. to   30.552 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.75379     ( -0.206975   0.201377 )
Norm@50keV  : 3.54964E-03    ( -0.000468821   0.000464285 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          37.89 using 59 PHA bins.
# Reduced chi-squared =         0.6648 for     57 degrees of freedom 
# Null hypothesis probability =   9.759348e-01
 
Photon flux (15-150 keV)    in 44.46 sec: 0.480663 ( -0.061352  0.061525 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.45616e-06 ( -1.96282e-07  1.98004e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from  -13.912 sec. to   30.552 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.242025     ( -1.09997   1.52114 )
Epeak [keV] : 53.0499      ( -9.33247 26.1023 )
Norm@50keV  : 2.31512E-02    ( -0.0232844   0.13233 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          31.87 using 59 PHA bins.
# Reduced chi-squared =         0.5690 for     56 degrees of freedom 
# Null hypothesis probability =   9.961142e-01
 
Photon flux (15-150 keV)    in 44.46 sec: 0.455222 ( -0.064553  0.064493 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.30927e-06 ( -2.15266e-07  2.25167e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   -0.052 sec. to    0.948 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.65489     ( -0.342275   0.327915 )
Norm@50keV  : 1.84159E-02    ( -0.00360975   0.00353464 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          53.31 using 59 PHA bins.
# Reduced chi-squared =         0.9352 for     57 degrees of freedom 
# Null hypothesis probability =   6.144445e-01
 
Photon flux (15-150 keV)    in 1 sec: 2.40865 ( -0.45316  0.45495 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.71214e-07 ( -3.50037e-08  3.55048e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.052 sec. to    0.948 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.65885     ( -0.338722   0.335621 )
Epeak [keV] : 9999.29      ( -9999.35 -9999.36 )
Norm@50keV  : 1.83929E-02    ( -0.00361546   0.0538232 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          53.31 using 59 PHA bins.
# Reduced chi-squared =         0.9519 for     56 degrees of freedom 
# Null hypothesis probability =   5.773696e-01
 
Photon flux (15-150 keV)    in 1 sec: 2.41654 ( -0.6992  0.46258 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.71945e-07 ( -3.68249e-08  2.7292e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 37.584 sec.
Hardness ratio (energy fluence ratio) = 1.18617817414

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

S(15-50 keV)  = 6.586499e-07
S(50-150 keV) = 7.975233e-07

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 = -9.668119387414844E-01, IMY = 6.865141750441269E-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:
-239.656000 -13.912000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
244.9751 -15.6384    0.9  49.2  147.9   9.1716  13.0    0.3	Sco X-1                       
205.7711  40.5708    3.1  22.6   11.1   0.5723   3.7 ------	UNKNOWN                       

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

Time interval of the image:
-13.912000 26.844600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
245.1062 -15.7328   44.1  49.4  147.9  -0.0671  -0.3    9.2	Sco X-1                       
158.2288  53.6702    2.3  52.4  -18.4   0.8063   5.0 ------	UNKNOWN                       
159.7144  51.0607    2.2  50.6  -21.0   0.7402   5.2 ------	UNKNOWN                       
192.4483 -29.1861    1.1  49.9 -144.6   2.0739  10.9 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
110.644630 902.374000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
135.5324 -40.5413    1.0  47.3 -164.9  10.2392  11.3    0.8	Vela X-1                      
170.7345 -60.6726    0.0  34.7  153.6  -0.9775  -1.4   12.7	Cen X-3                       
186.6370 -62.7753    0.8  33.8  139.8   9.9379  14.5    0.6	GX 301-2                      
204.6188 -29.8263    2.5  10.6   51.5   1.6494   4.6 ------	UNKNOWN                       
134.4576 -45.7166    2.8  47.8 -171.9   3.4046   4.1 ------	UNKNOWN                       
159.4309  -2.4469    2.8  41.2 -100.8   9.9346   4.2 ------	UNKNOWN