GRB180821A: 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: Fri Oct 19 18:32:47 EDT 2018
             Host Name: bat1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger854578
======================================================================

  Trigger: 00854578      Segment: 000

  BAT Trigger Time: 556562456   [s; MET]
      Trigger Stop: 556562576   [s; MET]
               UTC: 2018-08-21T16:40:34.535440    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 7.76306090448872   Dec: -38.6188964142254  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    7.81
     Image Trigger?:     YES
     Rate S/N Ratio:     0  [ if not an image trigger ]
     Image S/N Ratio:    7.81

  Analysis Position:   [ source = BAT ]
    RA: 7.76306090448872   Dec: -38.6188964142254  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 7.73884973621716   Dec: -38.6110706160199  [deg; J2000]  
        { 00h 30m 57.3s , -38d 36' 39.9" }
         +/- 2.31879286945561 [arcmin] (estimated 90% radius based on SNR)
         +/- 1.1733489518204 [arcmin] (formal 1-sigma fit error)
    SNR: 9.14777734485812
 
  Angular difference between the analysis and refined position is 1.228342 arcmin
 
  Partial Coding Fraction: 0.1757812    [ including projection effects ]

  Duration
     T90: 64 +/- 22.6274169979695
        Measured from: 1
                   to: 65     [s; relative to TRIGTIME]
     T50: 32 +/- 16
        Measured from: 17
                   to: 49     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 56.5     
                   to: 57.5     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: 1     
                   to: 65     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.744472   0.748213   0.689712  -0.002614
           0.127149   0.131331   0.113710   0.094822 [error]
 Peak      0.008439   0.023352   0.031360  -0.014636
           0.014743   0.015956   0.015483   0.011746 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   64.000    1.000   65.000
T90    64.000    1.000   65.000
T50    32.000   17.000   49.000
Peak    1.000   56.500   57.500
 
 
====== 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      -1.784    -0.311      0.293       -           -               -         2.48e-03     -4.52e-04          4.38e-04      57.060   57
CPL     -1.789    -0.353      0.300     9999.360    -9999.350      -9999.360      2.47e-03     -2.47e-03          7.03e-03      57.060   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      -2.309      2.309     2.309       -           -               -         1.58e-03     -1.58e-03          2.74e-03      68.880   57
CPL      4.269     -6.253    -4.269       59.570     -23.059        27.226      1.14e+00     -1.14e+00          4.06e+05      66.480   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   2.64e-07  4.09e-07  4.75e-07  1.06e-06  1.46e-06  2.21e-06   erg/cm2
      90%_error_low -6.68e-08 -6.72e-08 -1.16e-07 -4.54e-07 -2.68e-07 -5.79e-07   erg/cm2
      90%_error_hi   7.09e-08  6.69e-08  1.14e-07  6.25e-07  2.71e-07  7.05e-07   erg/cm2
Peak flux       PL   1.42e-01  8.93e-02  3.62e-02  1.99e-02  2.77e-01  2.87e-01   ph/cm2/s
      90%_error_low -1.42e-01 -8.93e-02 -3.62e-02 -1.99e-02 -2.77e-01 -2.87e-01   ph/cm2/s
      90%_error_hi   2.56e-01  1.33e-01  7.61e-02  1.65e-01  4.10e-01  4.24e-01   ph/cm2/s
 
Fluence        CPL   2.65e-07  4.08e-07  4.73e-07  1.08e-06  1.46e-06  2.13e-06   erg/cm2
      90%_error_low -4.74e-08 -6.46e-08 -1.30e-07 -5.51e-07 -2.49e-07 -8.22e-07   erg/cm2
      90%_error_hi   7.28e-08  6.85e-08  1.31e-07  3.66e-07  2.26e-07  6.48e-07   erg/cm2
Peak flux      CPL   2.43e-03  8.60e-02  1.80e-01  5.30e-03  2.65e-01  2.63e-01   ph/cm2/s
      90%_error_low     N/A   -8.60e-02     N/A   -5.30e-03 -2.65e-01 -2.63e-01   ph/cm2/s
      90%_error_hi      N/A    2.49e-01     N/A    4.23e-02  3.96e-01  3.98e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
    7.7388   -38.6111   0.0212    44.8344    32.5853         2.4852534      9.148 TRIG_00854578                 
 
Foreground time interval of the image:
  1.000  65.000 (delta_t =  64.000 [sec])
Background time interval of the image:
-239.000   1.000 (delta_t = 240.000 [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    1.000 sec. to   65.000 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.78449     ( -0.311454   0.292568 )
Norm@50keV  : 2.47621E-03    ( -0.000452055   0.000438447 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          57.06 using 59 PHA bins.
# Reduced chi-squared =          1.001 for     57 degrees of freedom 
# Null hypothesis probability =   4.729754e-01
 
Photon flux (15-150 keV)    in 64 sec: 0.339203 ( -0.056432  0.056578 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.46006e-06 ( -2.6791e-07  2.71153e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    1.000 sec. to   65.000 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.78897     ( -0.355263   0.297864 )
Epeak [keV] : 9999.36      ( -9999.35 -9999.36 )
Norm@50keV  : 2.47290E-03    ( -0.00247715   0.00702307 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          57.06 using 59 PHA bins.
# Reduced chi-squared =          1.019 for     56 degrees of freedom 
# Null hypothesis probability =   4.355343e-01
 
Photon flux (15-150 keV)    in 64 sec: 0.339561 ( -0.057304  0.056423 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.46174e-06 ( -2.49386e-07  2.26444e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   56.500 sec. to   57.500 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -2.30923     ( 2.30103   2.30103 )
Norm@50keV  : 1.58389E-03    ( -0.00158701   0.00273209 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          68.88 using 59 PHA bins.
# Reduced chi-squared =          1.208 for     57 degrees of freedom 
# Null hypothesis probability =   1.345919e-01
 
Photon flux (15-150 keV)    in 1 sec: 0.277391 ( -0.277391  0.409946 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.51688e-08 ( 1  2.45568e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   56.500 sec. to   57.500 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 9.99975     ( -11.984   -9.99996 )
Epeak [keV] : 64.5375      ( -28.0264 22.2579 )
Norm@50keV  : 68.4758    ( -68.2911   405795 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          66.15 using 59 PHA bins.
# Reduced chi-squared =          1.181 for     56 degrees of freedom 
# Null hypothesis probability =   1.664322e-01
 
Photon flux (15-150 keV)    in 1 sec: 0.264905 ( -0.264905  0.395625 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.50374e-08 ( -2.07568e-08  2.47042e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 64.0 sec.
Hardness ratio (energy fluence ratio) = 1.16115458619

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

S(15-50 keV)  = 6.731804e-07
S(50-150 keV) = 7.86872e-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 = 8.377328163679286E-01, IMY = -5.354491757685966E-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:
-239.000000 1.000000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
358.2452 -21.8467    2.4  37.1   58.7   2.2558   4.7 ------	UNKNOWN                       
 18.5726  -5.7641    2.3  11.7   55.3   0.9778   5.0 ------	UNKNOWN                       
 17.9683  57.1482    2.7  54.9 -174.3   3.8629   4.4 ------	UNKNOWN                       
 66.4237 -11.8905    3.4  42.1  -57.4   2.2577   3.4 ------	UNKNOWN                       

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

Time interval of the image:
1.000000 65.000000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
  1.6625 -42.2710    2.7  50.3   35.5   2.1267   4.3 ------	UNKNOWN                       
359.9424 -23.6132    2.5  37.0   54.7   1.0482   4.7 ------	UNKNOWN                       
  7.7388 -38.6111    1.3  44.8   32.6   2.4851   9.1 ------	UNKNOWN                       
 22.6194  -1.5550    2.3   5.9   55.3   0.4683   5.0 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
199.100600 581.900600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
  2.3608 -29.3061    2.7  10.3  124.0   1.2946   4.2 ------	UNKNOWN                       
352.4782 -74.9369    2.8  37.0  -22.2   1.6197   4.1 ------	UNKNOWN                       
 34.0902 -43.9836    3.2  20.4  -95.0   1.2358   3.6 ------	UNKNOWN                       
347.0680 -80.8772    2.8  42.9  -24.0   2.1231   4.2 ------	UNKNOWN                       
 69.3140 -63.0191    3.5  43.5  -64.1   4.9445   3.3 ------	UNKNOWN                       
 58.1524 -18.3820    3.7  48.0 -128.9   4.4590   3.1 ------	UNKNOWN