GRB181228A: 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: Sun Mar 17 23:08:15 EDT 2019
             Host Name: bat1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger879909
======================================================================

  Trigger: 00879909      Segment: 000

  BAT Trigger Time: 567658419.776   [s; MET]
      Trigger Stop: 567658420.8   [s; MET]
               UTC: 2018-12-28T02:53:17.622120    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 49.8308137189391   Dec: 13.1949402078414  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    15.47
     Image Trigger?:     NO
     Rate S/N Ratio:     53.7494186015068  [ if not an image trigger ]
     Image S/N Ratio:    15.47

  Analysis Position:   [ source = BAT ]
    RA: 49.8308137189391   Dec: 13.1949402078414  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 49.8313521505304   Dec: 13.2108052618726  [deg; J2000]  
        { 03h 19m 19.5s , +13d 12' 38.9" }
         +/- 0.759844524461702 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.190693863516596 [arcmin] (formal 1-sigma fit error)
    SNR: 45.0310020392225
 
  Angular difference between the analysis and refined position is 0.952423 arcmin
 
  Partial Coding Fraction: 0.3046875    [ including projection effects ]

  Duration
     T90: 255.152000069618 +/- 138.024949557979
        Measured from: -0.960000038146973
                   to: 254.192000031471     [s; relative to TRIGTIME]
     T50: 10.5759999752045 +/- 0.593942789707118
        Measured from: 3.53600001335144
                   to: 14.1119999885559     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 13.0759999752045     
                   to: 14.0759999752045     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -3.98399996757507     
                   to: 337.93599998951     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     3.913467   5.830245   4.647274   1.254401
           0.133443   0.142740   0.130047   0.114840 [error]
 Peak      0.252733   0.380318   0.412520   0.140043
           0.017857   0.020389   0.021435   0.016227 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100  341.920   -3.984  337.936
T90   255.152   -0.960  254.192
T50    10.576    3.536   14.112
Peak    1.000   13.076   14.076
 
 
====== 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      -1.442    -0.056      0.056       -           -               -         3.17e-03     -9.36e-05          9.36e-05      52.690   57
CPL     -1.241    -0.213      0.227      205.684     -80.573      -205.684      3.92e-03     -7.74e-04          1.04e-03      50.150   56
 
 
=== 1-s peak spectral analysis ===
(Best model with acceptable fit: N/A)
 
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      -1.129     -0.099     0.100       -           -               -         8.14e-02     -4.43e-03          4.43e-03      44.590   57
CPL     -1.079     -0.146     0.219      975.832    -975.832      -975.832      8.61e-02     -8.72e-03          8.07e-03      45.020   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   1.31e-06  2.49e-06  3.67e-06  1.16e-05  1.04e-05  1.90e-05   erg/cm2
      90%_error_low -7.67e-08 -8.53e-08 -1.34e-07 -9.45e-07 -3.28e-07 -1.02e-06   erg/cm2
      90%_error_hi   7.85e-08  8.50e-08  1.34e-07  1.00e-06  3.29e-07  1.07e-06   erg/cm2
Peak flux       PL   6.62e-04  9.54e-03  8.80e-02  9.59e+00  3.92e-01  9.60e+00   ph/cm2/s
      90%_error_low     N/A   -3.97e-04     N/A   -5.67e-01     N/A   -4.74e-01   ph/cm2/s
      90%_error_hi      N/A    1.19e-03     N/A    6.12e-01     N/A    7.34e-01   ph/cm2/s
 
Fluence        CPL   1.25e-06  2.52e-06  3.73e-06  8.78e-06  1.02e-05  1.63e-05   erg/cm2
      90%_error_low -9.81e-08 -9.24e-08 -1.49e-07 -2.18e-06 -3.65e-07 -2.19e-06   erg/cm2
      90%_error_hi   1.00e-07  9.32e-08  1.50e-07  3.03e-06  3.63e-07  2.76e-06   erg/cm2
Peak flux      CPL   2.35e+00  2.94e+00  2.68e+00  4.28e+00  9.53e+00  1.28e+01   ph/cm2/s
      90%_error_low     N/A       N/A       N/A       N/A   -5.91e-01 -1.69e+00   ph/cm2/s
      90%_error_hi      N/A       N/A       N/A       N/A    4.67e-01  2.08e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   49.8314    13.2108   0.0043    32.8476   114.5651        12.2585964     45.031 TRIG_00879909                 
 
Foreground time interval of the image:
 -3.984  14.525 (delta_t =  18.509 [sec])
Background time interval of the image:
-239.776  -3.984 (delta_t = 235.792 [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   -3.984 sec. to  337.936 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.44179     ( -0.0559068   0.0559262 )
Norm@50keV  : 3.16604E-03    ( -9.35941e-05   9.35892e-05 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          52.69 using 59 PHA bins.
# Reduced chi-squared =         0.9243 for     57 degrees of freedom 
# Null hypothesis probability =   6.374903e-01
 
Photon flux (15-150 keV)    in 341.9 sec: 0.389391 ( -0.012515  0.012547 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.03755e-05 ( -3.28209e-07  3.28818e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -3.984 sec. to  337.936 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.24062     ( -0.212972   0.226753 )
Epeak [keV] : 205.684      ( -80.5734 -205.684 )
Norm@50keV  : 3.92176E-03    ( -0.000773815   0.00103748 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          50.15 using 59 PHA bins.
# Reduced chi-squared =         0.8956 for     56 degrees of freedom 
# Null hypothesis probability =   6.947670e-01
 
Photon flux (15-150 keV)    in 341.9 sec: 0.383942 ( -0.013709  0.013747 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.02303e-05 ( -3.64831e-07  3.62917e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   13.076 sec. to   14.076 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.12941     ( -0.099488   0.0999643 )
Norm@50keV  : 8.14224E-02    ( -0.0044288   0.00442809 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          44.59 using 59 PHA bins.
# Reduced chi-squared =         0.7822 for     57 degrees of freedom 
# Null hypothesis probability =   8.841781e-01
 
Photon flux (15-150 keV)    in 1 sec: 0.391955 (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.43568e-07 ( -5.17051e-08  5.19205e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   13.076 sec. to   14.076 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.12453     ( -0.146512   0.219001 )
Epeak [keV] : 9999.17      ( -9999.18 -9999.18 )
Norm@50keV  : 8.18463E-02    ( -0.00444841   0.0123419 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          44.62 using 59 PHA bins.
# Reduced chi-squared =         0.7968 for     56 degrees of freedom 
# Null hypothesis probability =   8.630299e-01
 
Photon flux (15-150 keV)    in 1 sec: 9.53318 ( -0.59109  0.46742 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.10892e-07 ( -3.17201e-08  2.11999e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 255.152 sec.
Hardness ratio (energy fluence ratio) = 1.47248230263

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

S(15-50 keV)  = 3.800995e-06
S(50-150 keV) = 6.574574e-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 = -2.684074174296271E-01, IMY = -5.871966875140635E-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:
-239.776000 -3.984000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
326.2310  38.3032    8.3  45.3  -46.4   0.9755   1.4    3.0	Cyg X-2                       
 40.9219  61.4473    1.0  41.4   29.4   5.4240  11.8 ------	UNKNOWN                       
  1.0458   7.5685    3.1  22.0 -121.6   1.0171   3.7  458.4	UNKNOWN                       
345.5597  22.1046    2.5  28.8  -74.2   1.5776   4.6 ------	UNKNOWN                       
  7.4523 -33.3622    2.8  57.5 -158.5   6.2320   4.0 ------	UNKNOWN                       

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

Time interval of the image:
-3.984000 14.524600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
325.9981  38.2962   10.4  45.5  -46.4  -0.2881  -1.1    8.3	Cyg X-2                       
 49.8314  13.2108    0.3  32.8  114.6  12.2580  45.0 ------	UNKNOWN                       
 49.9414  24.2427    2.8  30.2   94.0   0.9531   4.1 ------	UNKNOWN                       
 45.5158  38.4625    4.1  28.6   63.9   0.5319   2.9 ------	UNKNOWN                       
 39.7592  30.8794    2.3  21.6   77.2   0.7236   4.9 ------	UNKNOWN                       
335.9956  58.2795    2.8  45.3  -16.7   0.7277   4.2 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
71.124600 962.314000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6269  22.0136    0.5  33.3   89.9  34.6751  21.9    0.4	Crab                          
 40.9509  61.4630    1.1  48.7   14.4  18.4075  10.4 ------	UNKNOWN                       
  8.3181  61.7510    2.8  56.9   -2.0  12.4929   4.1 ------	UNKNOWN                       
358.4149  57.8487    3.1  58.9   -9.1  12.6686   3.8 ------	UNKNOWN