GRB230228A: 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: Wed Jun 14 15:11:02 EDT 2023
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1156572
======================================================================

  Trigger: 01156572      Segment: 000

  BAT Trigger Time: 699256281.088   [s; MET]
      Trigger Stop: 699256282.112   [s; MET]
               UTC: 2023-02-28T05:50:50.250320    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 18.4033334147616   Dec: 44.4885974077295  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    11.96
     Image Trigger?:     NO
     Rate S/N Ratio:     25.0399680510978  [ if not an image trigger ]
     Image S/N Ratio:    11.96

  Analysis Position:   [ source = BAT ]
    RA: 18.4033334147616   Dec: 44.4885974077295  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 18.3972021614032   Dec: 44.4951400827483  [deg; J2000]  
        { 01h 13m 35.3s , +44d 29' 42.5" }
         +/- 1.52845401109954 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.539801363901666 [arcmin] (formal 1-sigma fit error)
    SNR: 16.5920749177262
 
  Angular difference between the analysis and refined position is 0.472197 arcmin
 
  Partial Coding Fraction: 0.7890625    [ including projection effects ]

  Duration
     T90: 2.1839998960495 +/- 0.396080751971004
        Measured from: 0.0759999752044678
                   to: 2.25999987125397     [s; relative to TRIGTIME]
     T50: 0.935999989509583 +/- 0.274167776963183
        Measured from: 0.48799991607666
                   to: 1.42399990558624     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 0.175999999046326     
                   to: 1.17599999904633     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -0.0480000972747803     
                   to: 2.52799999713898     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.185227   0.243741   0.163161   0.034179
           0.020787   0.022164   0.019679   0.015222 [error]
 Peak      0.088646   0.145998   0.120238   0.021618
           0.013194   0.015200   0.014097   0.010303 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100    2.576   -0.048    2.528
T90     2.184    0.076    2.260
T50     0.936    0.488    1.424
Peak    1.000    0.176    1.176
 
 
====== 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      -1.654    -0.173      0.168       -           -               -         1.55e-02     -1.73e-03          1.71e-03      52.760   57
CPL     -0.868    -0.692      0.832       66.674     -15.865       125.302      4.13e-02     -2.35e-02          7.40e-02      48.910   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      -1.470     -0.188     0.183       -           -               -         2.49e-02     -2.99e-03          2.97e-03      49.840   57
CPL     -0.483     -0.788     0.954       78.316     -18.345       101.485      7.79e-02     -4.60e-02          1.51e-01      45.100   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   5.89e-08  9.85e-08  1.25e-07  3.19e-07  3.71e-07  6.01e-07   erg/cm2
      90%_error_low -9.01e-09 -1.02e-08 -1.82e-08 -8.47e-08 -4.36e-08 -1.04e-07   erg/cm2
      90%_error_hi   9.29e-09  1.02e-08  1.82e-08  1.02e-07  4.40e-08  1.18e-07   erg/cm2
Peak flux       PL   9.94e-01  1.02e+00  7.35e-01  8.50e-01  3.08e+00  3.60e+00   ph/cm2/s
      90%_error_low -1.79e-01 -1.23e-01 -1.09e-01 -2.25e-01 -3.58e-01 -4.28e-01   ph/cm2/s
      90%_error_hi   1.88e-01  1.23e-01  1.08e-01  2.65e-01  3.59e-01  4.32e-01   ph/cm2/s
 
Fluence        CPL   5.36e-08  1.09e-07  1.28e-07  1.04e-07  3.50e-07  3.95e-07   erg/cm2
      90%_error_low -1.03e-08 -1.35e-08 -2.08e-08    N/A    -4.72e-08 -7.91e-08   erg/cm2
      90%_error_hi   1.04e-08  1.41e-08  2.06e-08    N/A     4.80e-08  1.69e-07   erg/cm2
Peak flux      CPL   8.34e-01  1.12e+00  8.11e-01  3.48e-01  3.00e+00  3.12e+00   ph/cm2/s
      90%_error_low -2.15e-01 -1.52e-01 -1.30e-01 -1.81e-01 -3.64e-01 -4.15e-01   ph/cm2/s
      90%_error_hi   2.24e-01  1.58e-01  1.34e-01  3.60e-01  3.64e-01  4.74e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   18.3972    44.4951   0.0116    30.8274   177.6719         0.6510766     16.592 TRIG_01156572                 
 
Foreground time interval of the image:
 -0.048   2.528 (delta_t =   2.576 [sec])
Background time interval of the image:
-214.187  -0.048 (delta_t = 214.139 [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   -0.048 sec. to    2.528 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.65393     ( -0.172721   0.168114 )
Norm@50keV  : 1.54891E-02    ( -0.00172643   0.00170713 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   52.76     using 59 bins.
 Reduced chi-squared = 0.925614
# Null hypothesis probability of 6.35e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 2.576 sec: 2.02520 ( -0.20911  0.20921 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.70993e-07 ( -4.35725e-08  4.40432e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.048 sec. to    2.528 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.867736     ( -0.691617   0.831939 )
Epeak [keV] : 66.6738      ( -15.8647 125.303 )
Norm@50keV  : 4.12526E-02    ( -0.0234598   0.0740318 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   48.91     using 59 bins.
 Reduced chi-squared = 0.873393
# Null hypothesis probability of 7.38e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 2.576 sec: 1.97928 ( -0.21333  0.21326 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.49579e-07 ( -4.72037e-08  4.79752e-08 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from    0.176 sec. to    1.176 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.47     ( -0.188163   0.182999 )
Norm@50keV  : 2.48570E-02    ( -0.00298944   0.00296857 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   49.84     using 59 bins.
 Reduced chi-squared = 0.874386
# Null hypothesis probability of 7.38e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 3.07884 ( -0.35834  0.35851 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.37039e-07 ( -3.11705e-08  3.1446e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    0.176 sec. to    1.176 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.483109     ( -0.787821   0.953529 )
Epeak [keV] : 78.3164      ( -18.3445 101.485 )
Norm@50keV  : 7.79032E-02    ( -0.0459525   0.151225 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   45.10     using 59 bins.
 Reduced chi-squared = 0.805357
# Null hypothesis probability of 8.51e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 3.00387 ( -0.36417  0.36407 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.26642e-07 ( -3.25311e-08  3.28895e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 2.184 sec.
Hardness ratio (energy fluence ratio) = 1.27113066804

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

S(15-50 keV)  = 1.5736876e-07
S(50-150 keV) = 2.136248e-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 = -5.962746286243424E-01, IMY = -2.424163367299306E-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:
-214.187400 -0.048000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
288.7174  11.0035    5.7  51.3   -4.8   1.5448   2.0    5.9	GRS 1915+105                  
299.5871  35.1973    1.2  29.0   17.2   5.2247   9.8    0.3	Cyg X-1                       
308.0886  40.9071    2.2  20.9   25.4   2.5386   5.3    2.9	Cyg X-3                       
326.2883  38.4052    6.7   8.0   -1.9   0.7682   1.7    7.4	Cyg X-2                       
 20.7909  80.2495    2.6  42.0  118.0  10.5999   4.4 ------	UNKNOWN                       
 45.6332  42.5021    2.5  50.2  171.8   9.2835   4.6 ------	UNKNOWN                       

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

Time interval of the image:
-0.048000 2.528000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
288.8718  10.8819    5.0  51.3   -5.0   0.1682   2.3    5.8	GRS 1915+105                  
299.6616  35.2549    6.5  28.9   17.3  -0.0661  -1.8    4.7	Cyg X-1                       
308.0131  40.8044    4.0  21.0   25.1   0.0964   2.9    9.9	Cyg X-3                       
326.2410  38.3085   55.4   8.1   -2.4  -0.0065  -0.2    3.4	Cyg X-2                       
282.4632  62.9132    2.7  37.5   70.8   0.3287   4.2 ------	UNKNOWN                       
 23.5939  65.7652    2.1  35.8  139.0   0.2809   5.6 ------	UNKNOWN                       
 18.3972  44.4951    0.7  30.8  177.7   0.6511  16.6 ------	UNKNOWN                       
 28.9192  23.1839    1.8  47.5 -156.6   0.4692   6.3 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
101.012600 718.025300
720.912000 963.092000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
299.6386  35.1960    3.0  58.8  -22.1  24.6103   3.9    2.4	Cyg X-1                       
308.0929  40.9751    4.6  50.1  -20.4   8.5108   2.5    1.6	Cyg X-3                       
326.0281  38.2912    3.6  39.1  -32.9  -6.5717  -3.2    7.0	Cyg X-2                       
259.9392  78.6988    5.4  51.6   34.7  11.6780   2.2 ------	UNKNOWN                       
 70.2844  44.5398    1.3  36.3  118.5  33.8950   8.7 ------	UNKNOWN                       
 63.6954  63.5508    2.8  31.7   84.5  11.8263   4.2 ------	UNKNOWN                       
298.0442  41.6223    2.7  56.3  -15.0  18.1296   4.3 ------	UNKNOWN                       
 28.6123   3.3947    5.5  42.1 -147.9   5.0967   2.1 ------	UNKNOWN                       
 25.2331  -1.6733    2.2  46.6 -142.0  16.5527   5.2 ------	UNKNOWN