Analysis Summary

Notes:

======================================================================
                  BAT GRB EVENT DATA PROCESSING REPORT
    Process Script Ver: batgrbproduct v2.46
    Process Start Time: Wed May 30 15:23:21 EDT 2018
             Host Name: bat1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger821881
======================================================================

  Trigger: 00821881      Segment: 000

  BAT Trigger Time: 544495556.416   [s; MET]
      Trigger Stop: 544495557.44   [s; MET]
               UTC: 2018-04-04T00:45:35.686520    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 83.5636225759874   Dec: -37.1698540029188  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    8.76
     Image Trigger?:     NO
     Rate S/N Ratio:     13.856406460551  [ if not an image trigger ]
     Image S/N Ratio:    8.76

  Analysis Position:   [ source = BAT ]
    RA: 83.5636225759874   Dec: -37.1698540029188  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 83.5313008011088   Dec: -37.1695522417724  [deg; J2000]  
        { 05h 34m 07.5s , -37d 10' 10.4" }
         +/- 1.08541244783242 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.417853299211083 [arcmin] (formal 1-sigma fit error)
    SNR: 27.0563163836033
 
  Angular difference between the analysis and refined position is 1.545441 arcmin
 
  Partial Coding Fraction: 0.8203125    [ including projection effects ]

  Duration
     T90: 36.2799999713898 +/- 5.35102610066606
        Measured from: -17.1360000371933
                   to: 19.1439999341965     [s; relative to TRIGTIME]
     T50: 10.1959999799728 +/- 1.75672875410864
        Measured from: -2.12800002098083
                   to: 8.067999958992     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 1.99199998378754     
                   to: 2.99199998378754     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -22.472000002861     
                   to: 24.1599999666214     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.860579   0.849977   0.514605   0.132736
           0.042551   0.043873   0.038234   0.033972 [error]
 Peak      0.046023   0.061991   0.037731   0.011676
           0.006742   0.006809   0.005948   0.005112 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   46.632  -22.472   24.160
T90    36.280  -17.136   19.144
T50    10.196   -2.128    8.068
Peak    1.000    1.992    2.992
 
 
====== 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      -1.949    -0.123      0.119       -           -               -         2.96e-03     -2.08e-04          2.05e-04      40.530   57
CPL     -1.948    -0.484      0.435     9986.040    -9986.030      -9986.040      2.97e-03     -1.20e-03          2.02e-03      40.530   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      -1.674     -0.228     0.223       -           -               -         1.00e-02     -1.39e-03          1.36e-03      54.340   57
CPL     -1.581     -0.826     0.790      202.949    -202.939      -202.949      1.13e-02        N/A               N/A         54.380   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   2.69e-07  3.77e-07  3.90e-07  7.42e-07  1.27e-06  1.78e-06   erg/cm2
      90%_error_low -2.59e-08 -2.23e-08 -3.83e-08 -1.42e-07 -8.57e-08 -1.79e-07   erg/cm2
      90%_error_hi   2.67e-08  2.24e-08  3.85e-08  1.63e-07  8.65e-08  1.95e-07   erg/cm2
Peak flux       PL   4.89e-01  4.44e-01  2.78e-01  2.66e-01  1.32e+00  1.48e+00   ph/cm2/s
      90%_error_low -9.67e-02 -5.69e-02 -4.96e-02 -8.41e-02 -1.67e-01 -1.87e-01   ph/cm2/s
      90%_error_hi   1.01e-01  5.67e-02  4.95e-02  1.06e-01  1.67e-01  1.88e-01   ph/cm2/s
 
Fluence        CPL   2.70e-07  3.76e-07  3.90e-07  7.42e-07  1.27e-06  1.81e-06   erg/cm2
      90%_error_low -3.17e-08 -2.15e-08 -4.09e-08    N/A    -1.05e-07 -2.36e-07   erg/cm2
      90%_error_hi   2.67e-08  2.83e-08  4.13e-08    N/A     8.65e-08  9.19e-08   erg/cm2
Peak flux      CPL   4.89e-01  4.44e-01  2.78e-01  2.66e-01  1.32e+00  1.48e+00   ph/cm2/s
      90%_error_low -1.06e-01 -5.62e-02 -4.95e-02 -1.68e-01 -1.70e-01 -2.64e-01   ph/cm2/s
      90%_error_hi   7.77e-02  7.21e-02  5.13e-02  6.02e-02  1.65e-01  1.86e-01   ph/cm2/s
 
======================================================================
  • Special notes of this burst




    Image

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

    #   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
       83.5313   -37.1696   0.0071    32.4939    -8.8360         2.2155130     27.056 TRIG_00821881                 
     
    Foreground time interval of the image:
    -22.472  17.685 (delta_t =  40.157 [sec])
    Background time interval of the image:
    -168.515 -22.472 (delta_t = 146.043 [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

    Bokeh Plot

    Other quick-look light curves:




    Spectra

    Notes:

    Time averaged spectrum fit using the average DRM

    Power-law model
    Time interval is from  -22.472 sec. to   24.160 sec.
     
    Spectral model in power-law:
    ------------------------------------------------------------
    Parameters  : value       lower 90%   higher 90%
    Photon index: -1.94863     ( -0.122586   0.119285 )
    Norm@50keV  : 2.96201E-03    ( -0.000207822   0.000204804 )
    ------------------------------------------------------------
    #Fit statistic : Chi-Squared =          40.53 using 59 PHA bins.
    # Reduced chi-squared =         0.7111 for     57 degrees of freedom 
    # Null hypothesis probability =   9.513769e-01
     
    Photon flux (15-150 keV)    in 46.63 sec: 0.434159 ( -0.026644  0.026731 ) ph/cm2/s
    Energy fluence (15-150 keV)             : 1.27123e-06 ( -8.56938e-08  8.6536e-08 ) ergs/cm2
     
    
    Cutoff power-law model
    Time interval is from  -22.472 sec. to   24.160 sec.
    Spectral model in the cutoff power-law:
    ------------------------------------------------------------
    Parameters  : value       lower 90%   higher 90%
    Photon index: -1.94756     ( -0.483438   0.435499 )
    Epeak [keV] : 9986.04      ( -9999.35 -9999.36 )
    Norm@50keV  : 2.96598E-03    ( -0.00119559   0.00202185 )
    ------------------------------------------------------------
    #Fit statistic : Chi-Squared =          40.53 using 59 PHA bins.
    # Reduced chi-squared =         0.7238 for     56 degrees of freedom 
    # Null hypothesis probability =   9.404426e-01
     
    Photon flux (15-150 keV)    in 46.63 sec: 0.434460 ( -0.028859  0.026524 ) ph/cm2/s
    Energy fluence (15-150 keV)             : 1.27451e-06 ( -1.0492e-07  8.65084e-08 ) ergs/cm2
     
    

    1-s peak spectrum fit

    Power-law model
    Time interval is from    1.992 sec. to    2.992 sec.
     
    Spectral model in power-law:
    ------------------------------------------------------------
    Parameters  : value       lower 90%   higher 90%
    Photon index: -1.67403     ( -0.227917   0.222956 )
    Norm@50keV  : 1.00462E-02    ( -0.00138905   0.00136394 )
    ------------------------------------------------------------
    #Fit statistic : Chi-Squared =          54.34 using 59 PHA bins.
    # Reduced chi-squared =         0.9533 for     57 degrees of freedom 
    # Null hypothesis probability =   5.756327e-01
     
    Photon flux (15-150 keV)    in 1 sec: 1.32242 ( -0.16719  0.16738 ) ph/cm2/s
    Energy fluence (15-150 keV)             : 9.32331e-08 ( -1.35071e-08  1.3729e-08 ) ergs/cm2
     
    
    Cutoff power-law model
    Time interval is from    1.992 sec. to    2.992 sec.
    Spectral model in the cutoff power-law:
    ------------------------------------------------------------
    Parameters  : value       lower 90%   higher 90%
    Photon index: -1.67255     ( -0.818515   0.797966 )
    Epeak [keV] : 9987.16      ( -9988.19 -9988.2 )
    Norm@50keV  : 1.00658E-02    (     )
    ------------------------------------------------------------
    #Fit statistic : Chi-Squared =          54.34 using 59 PHA bins.
    # Reduced chi-squared =         0.9703 for     56 degrees of freedom 
    # Null hypothesis probability =   5.380717e-01
     
    Photon flux (15-150 keV)    in 1 sec: 1.32235 ( -0.16983  0.1654 ) ph/cm2/s
    Energy fluence (15-150 keV)             : 9.3218e-08 ( -1.55897e-08  1.35989e-08 ) ergs/cm2
     
    

    Time-resolved spectra




    Distribution

    T90 vs. Hardness ratio plot

    T90                                   = 36.28 sec.
    Hardness ratio (energy fluence ratio) = 1.03628709343
    

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

    S(15-50 keV)  = 6.459347e-07
    S(50-150 keV) = 6.252902e-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 = 6.293607744657843E-01, IMY = 9.783533358478688E-02
    

    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:
    -168.515400 -22.472000
     
    # RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
    #  [deg]    [deg]    ['] [deg]  [deg]                   [']
    135.5295 -40.4988    3.0  40.3   60.6   1.7793   3.9    3.4	Vela X-1                      
    170.0065 -60.7209   17.9  34.8  108.7  -0.2082  -0.6   10.8	Cen X-3                       
    186.7051 -62.7325    4.5  37.8  121.5   0.9481   2.5    2.6	GX 301-2                      
    

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

    Time interval of the image:
    -22.472000 17.684590
     
    # RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
    #  [deg]    [deg]    ['] [deg]  [deg]                   [']
    135.5761 -40.6645    4.1  40.2   60.8   0.6496   2.8    6.9	Vela X-1                      
    170.6322 -60.5262    0.0  35.2  108.9   0.2242   1.3   11.0	Cen X-3                       
    186.9203 -62.9287    8.0  37.7  121.8  -0.2799  -1.4   11.9	GX 301-2                      
    193.6839 -61.2235    2.3  40.8  124.7   1.2011   4.9 ------	UNKNOWN                       
    263.9902 -54.5446    2.9  55.8  169.6   1.7961   4.0 ------	UNKNOWN                       
     83.5318 -37.1693    0.4  32.5   -8.8   2.2289  27.2 ------	UNKNOWN                       
    352.2167 -61.2145    2.6  34.4 -134.0   0.5081   4.5 ------	UNKNOWN                       
      0.0815 -52.4318    2.4  39.1 -119.6   0.8566   4.9 ------	UNKNOWN                       
    

    Post-slew image of 15-350 keV band

    Time interval of the image:
    70.484600 842.784000
     
    # RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
    #  [deg]    [deg]    ['] [deg]  [deg]                   [']
     83.6459  22.0213    1.8  59.2  -16.3  15.3713   6.6    0.8	Crab                          
    135.3986 -40.5316    7.8  39.9   95.0   2.4005   1.5    6.1	Vela X-1                      
    124.9454 -59.5672    4.0  34.5  127.5   1.9774   2.9 ------	UNKNOWN                       
     90.9563 -31.8608    2.7   8.1   34.7   1.4971   4.3 ------	UNKNOWN                       
     14.4730 -50.3113    2.6  49.7 -144.9   6.4576   4.5 ------	UNKNOWN                       
     48.5580 -12.0954    3.9  40.1  -76.9   4.3454   2.9 ------	UNKNOWN                       
     55.3935   0.1386    3.1  45.5  -57.8   7.5630   3.7 ------	UNKNOWN                       
     21.1709 -39.2988    3.0  48.1 -129.1   8.2787   3.8 ------	UNKNOWN