GRB230826A: 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 v2.48
    Process Start Time: Fri Sep 29 23:24:33 EDT 2023
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1187463
======================================================================

  Trigger: 01187463      Segment: 000

  BAT Trigger Time: 714771198.976   [s; MET]
      Trigger Stop: 714771200   [s; MET]
               UTC: 2023-08-26T19:32:47.078920    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 83.0117437221934   Dec: 66.124903377032  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    15.04
     Image Trigger?:     NO
     Rate S/N Ratio:     45.902069670114  [ if not an image trigger ]
     Image S/N Ratio:    15.04

  Analysis Position:   [ source = BAT ]
    RA: 83.0117437221934   Dec: 66.124903377032  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 83.049639325098   Dec: 66.1248572518743  [deg; J2000]  
        { 05h 32m 11.9s , +66d 07' 29.5" }
         +/- 0.6182241087203 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.192837617292267 [arcmin] (formal 1-sigma fit error)
    SNR: 60.4618354446474
 
  Angular difference between the analysis and refined position is 0.920286 arcmin
 
  Partial Coding Fraction: 0.875    [ including projection effects ]

  Duration
     T90: 40.8399999141693 +/- 1.65832214332882
        Measured from: -2.75199997425079
                   to: 38.0879999399185     [s; relative to TRIGTIME]
     T50: 12.1879999637604 +/- 0.865572549812708
        Measured from: 1.95600008964539
                   to: 14.1440000534058     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 2.43599998950958     
                   to: 3.43599998950958     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -6.31199991703033     
                   to: 47.4800000190735     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     1.682061   2.375795   1.714021   0.390432
           0.048673   0.051504   0.044676   0.035144 [error]
 Peak      0.079874   0.158113   0.118059   0.028862
           0.007585   0.008988   0.008368   0.005867 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   53.792   -6.312   47.480
T90    40.840   -2.752   38.088
T50    12.188    1.956   14.144
Peak    1.000    2.436    3.436
 
 
====== 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: CPL)
 
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      -1.520    -0.052      0.052       -           -               -         7.34e-03     -2.04e-04          2.03e-04      59.780   57
CPL     -1.215    -0.207      0.217      136.965     -35.712       161.221      1.02e-02     -2.00e-03          2.63e-03      53.300   56
 
 
=== 1-s peak spectral analysis ===
(Best model with acceptable fit: CPL)
 
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      -1.230     -0.108     0.108       -           -               -         2.53e-02     -1.71e-03          1.70e-03      57.000   57
CPL     -0.235     -0.511     0.589       88.509     -16.906        42.198      8.11e-02     -3.59e-02          7.87e-02      44.590   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   5.14e-07  9.32e-07  1.30e-06  3.79e-06  3.73e-06  6.53e-06   erg/cm2
      90%_error_low -2.75e-08 -2.92e-08 -4.56e-08 -2.93e-07 -1.10e-07 -3.21e-07   erg/cm2
      90%_error_hi   2.81e-08  2.91e-08  4.55e-08  3.10e-07  1.10e-07  3.34e-07   erg/cm2
Peak flux       PL   8.05e-01  9.51e-01  8.11e-01  1.17e+00  2.98e+00  3.74e+00   ph/cm2/s
      90%_error_low -9.21e-02 -7.03e-02 -6.51e-02 -1.80e-01 -2.01e-01 -2.69e-01   ph/cm2/s
      90%_error_hi   9.51e-02  6.99e-02  6.48e-02  1.99e-01  2.02e-01  2.72e-01   ph/cm2/s
 
Fluence        CPL   4.80e-07  9.51e-07  1.33e-06  2.50e-06  3.65e-06  5.26e-06   erg/cm2
      90%_error_low -3.49e-08 -3.22e-08 -5.00e-08 -5.80e-07 -1.24e-07 -5.89e-07   erg/cm2
      90%_error_hi   3.55e-08  3.24e-08  5.04e-08  7.95e-07  1.24e-07  7.97e-07   erg/cm2
Peak flux      CPL   6.79e-01  1.05e+00  8.77e-01  4.30e-01  2.89e+00  3.04e+00   ph/cm2/s
      90%_error_low -1.09e-01 -8.88e-02 -7.67e-02 -1.65e-01 -2.09e-01 -2.64e-01   ph/cm2/s
      90%_error_hi   1.12e-01  9.15e-02  7.78e-02  2.62e-01  2.08e-01  3.11e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   83.0496    66.1249   0.0032    15.6548    46.2238         4.7220723     60.462 TRIG_01187463                 
 
Foreground time interval of the image:
 -6.312  13.325 (delta_t =  19.637 [sec])
Background time interval of the image:
-239.976  -6.312 (delta_t = 233.664 [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   -6.312 sec. to   47.480 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.52049     ( -0.0522866   0.0522357 )
Norm@50keV  : 7.33766E-03    ( -0.000203507   0.000203461 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   59.78     using 59 bins.
 Reduced chi-squared = 1.04877
# Null hypothesis probability of 3.75e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 53.79 sec: 0.921191 ( -0.027714  0.027787 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.73251e-06 ( -1.10239e-07  1.10495e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -6.312 sec. to   47.480 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.21479     ( -0.207147   0.217435 )
Epeak [keV] : 136.965      ( -35.7123 161.221 )
Norm@50keV  : 1.02161E-02    ( -0.00200262   0.0026341 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   53.30     using 59 bins.
 Reduced chi-squared = 0.951786
# Null hypothesis probability of 5.78e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 53.79 sec: 0.901297 ( -0.030498  0.030588 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.64848e-06 ( -1.24352e-07  1.23954e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from    2.436 sec. to    3.436 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.22983     ( -0.107993   0.108258 )
Norm@50keV  : 2.53140E-02    ( -0.00170553   0.00170429 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   57.00     using 59 bins.
 Reduced chi-squared = 1
# Null hypothesis probability of 4.75e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.98445 ( -0.20147  0.20154 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.54736e-07 ( -1.9372e-08  1.95161e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    2.436 sec. to    3.436 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.234942     ( -0.510534   0.589257 )
Epeak [keV] : 88.5089      ( -16.9041 42.1998 )
Norm@50keV  : 8.10734E-02    ( -0.0359158   0.0786656 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   44.59     using 59 bins.
 Reduced chi-squared = 0.79625
# Null hypothesis probability of 8.64e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.89044 ( -0.20886  0.20786 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.35879e-07 ( -2.21025e-08  2.21093e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 40.84 sec.
Hardness ratio (energy fluence ratio) = 1.39601491752

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

S(15-50 keV)  = 1.4309767e-06
S(50-150 keV) = 2.2175008e-06

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 = 1.938793204284003E-01, IMY = -2.023434344718492E-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:
-239.976000 -6.312000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6146  22.0309    1.5  54.3    1.6   8.0728   7.4    1.4	Crab                          
 34.3495  64.0310    3.9  32.0   77.2   2.0291   2.9 ------	UNKNOWN                       
136.3386  48.1186    3.3  23.3  -66.9   1.3384   3.5 ------	UNKNOWN                       

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

Time interval of the image:
-6.312000 13.324600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6882  21.8462    0.0  54.4    1.4   0.6274   1.8   10.5	Crab                          
254.3482  64.6411    3.2  40.2  163.6   0.4714   3.6 ------	UNKNOWN                       
 83.0497  66.1248    0.2  15.7   46.2   4.7223  60.5 ------	UNKNOWN                       
127.7589  22.8597    2.6  47.9  -50.9   1.4286   4.4 ------	UNKNOWN                       
164.0996  35.2941    3.2  41.1  -99.1   1.1724   3.6 ------	UNKNOWN                       
132.9889  25.3293    3.8  45.7  -57.6   1.0401   3.1 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
61.724600 962.072300
1001.024000 1091.064000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6066  22.0277    0.8  44.1  -12.8  37.0084  14.1    1.7	Crab                          
333.0297  68.2769    2.6  37.0  132.7  14.4411   4.4 ------	UNKNOWN                       
 40.8020  61.4735    2.2  18.8   83.8   8.4474   5.2 ------	UNKNOWN                       
 62.2305  46.9493    2.8  22.1   28.1   6.8658   4.1 ------	UNKNOWN                       
112.2560  48.3853    3.2  23.3  -67.0   6.2779   3.7 ------	UNKNOWN                       
157.8090  60.2094    2.9  32.2 -127.8   7.4256   4.0 ------	UNKNOWN