GRB240218A: 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: Sat Mar  9 13:56:06 EST 2024
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1215912
======================================================================

  Trigger: 01215912      Segment: 000

  BAT Trigger Time: 729914433.6   [s; MET]
      Trigger Stop: 729914434.624   [s; MET]
               UTC: 2024-02-18T02:00:00.666060    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 161.780800958629   Dec: 1.30403195307657  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    6.54
     Image Trigger?:     NO
     Rate S/N Ratio:     11.3578166916005  [ if not an image trigger ]
     Image S/N Ratio:    6.54

  Analysis Position:   [ source = BAT ]
    RA: 161.780800958629   Dec: 1.30403195307657  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 161.805780547244   Dec: 1.28978262037998  [deg; J2000]  
        { 10h 47m 13.4s , +01d 17' 23.2" }
         +/- 1.18607054720025 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.403427351333368 [arcmin] (formal 1-sigma fit error)
    SNR: 23.8367041565111
 
  Angular difference between the analysis and refined position is 1.725147 arcmin
 
  Partial Coding Fraction: 0.3671875    [ including projection effects ]

  Duration
     T90: 258.031999945641 +/- 26.735401600844
        Measured from: -9.1360000371933
                   to: 248.895999908447     [s; relative to TRIGTIME]
     T50: 46.663999915123 +/- 20.1574869038965
        Measured from: 5.15199995040894
                   to: 51.8159998655319     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 21.6200000047684     
                   to: 22.6200000047684     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -19.2239999771118     
                   to: 315.299999952316     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     2.980683   3.712684   2.676311   0.753564
           0.133237   0.139926   0.120496   0.101388 [error]
 Peak      0.070137   0.134645   0.119807   0.026716
           0.012242   0.013704   0.012834   0.009127 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100  334.524  -19.224  315.300
T90   258.032   -9.136  248.896
T50    46.664    5.152   51.816
Peak    1.000   21.620   22.620
 
 
====== 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      -1.619    -0.080      0.080       -           -               -         1.98e-03     -8.78e-05          8.75e-05      60.420   57
CPL     -1.408    -0.249      0.340      142.140     -58.532      -142.140      2.52e-03     -6.00e-04          1.17e-03      59.150   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      -1.405     -0.182     0.180       -           -               -         2.42e-02     -2.76e-03          2.75e-03      67.270   57
CPL     -0.305     -0.814     0.990       80.183     -17.742        78.349      8.36e-02     -4.95e-02          1.63e-01      61.690   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   9.47e-07  1.62e-06  2.11e-06  5.55e-06  6.19e-06  1.02e-05   erg/cm2
      90%_error_low -7.31e-08 -7.47e-08 -1.22e-07 -6.75e-07 -2.90e-07 -7.67e-07   erg/cm2
      90%_error_hi   7.50e-08  7.45e-08  1.22e-07  7.36e-07  2.92e-07  8.15e-07   erg/cm2
Peak flux       PL   9.10e-01  9.69e-01  7.32e-01  8.99e-01  2.95e+00  3.51e+00   ph/cm2/s
      90%_error_low -1.68e-01 -1.18e-01 -1.00e-01 -2.25e-01 -3.37e-01 -4.03e-01   ph/cm2/s
      90%_error_hi   1.77e-01  1.17e-01  9.94e-02  2.63e-01  3.38e-01  4.06e-01   ph/cm2/s
 
Fluence        CPL   9.10e-07  1.65e-06  2.13e-06  4.04e-06  6.08e-06  8.74e-06   erg/cm2
      90%_error_low -9.04e-08 -8.71e-08 -1.30e-07 -1.47e-06 -3.31e-07 -1.50e-06   erg/cm2
      90%_error_hi   9.21e-08  8.84e-08  1.31e-07  1.66e-06  3.29e-07  1.80e-06   erg/cm2
Peak flux      CPL   7.31e-01  1.06e+00  8.13e-01  3.48e-01  2.85e+00  2.95e+00   ph/cm2/s
      90%_error_low -2.05e-01 -1.42e-01 -1.22e-01 -1.76e-01 -3.48e-01 -3.99e-01   ph/cm2/s
      90%_error_hi   2.16e-01  1.46e-01  1.25e-01  3.43e-01  3.48e-01  4.59e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  161.8058     1.2898   0.0081    35.0877   131.0785         3.5812795     23.837 TRIG_01215912                 
 
Foreground time interval of the image:
-19.224  10.501 (delta_t =  29.725 [sec])
Background time interval of the image:
-239.600 -19.224 (delta_t = 220.376 [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  -19.224 sec. to  315.300 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.61914     ( -0.0803192   0.0798526 )
Norm@50keV  : 1.98215E-03    ( -8.77709e-05   8.74555e-05 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   60.42     using 59 bins.
 Reduced chi-squared = 1.06
# Null hypothesis probability of 3.53e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 334.5 sec: 0.256257 ( -0.011703  0.011731 ) ph/cm2/s
Energy fluence (15-150 keV)             : 6.18765e-06 ( -2.90444e-07  2.91623e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from  -19.224 sec. to  315.300 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.40789     ( -0.248745   0.340438 )
Epeak [keV] : 142.140      ( -58.5391 -142.147 )
Norm@50keV  : 2.52244E-03    ( -0.000599555   0.00116696 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   59.15     using 59 bins.
 Reduced chi-squared = 1.05625
# Null hypothesis probability of 3.61e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 334.5 sec: 0.252950 ( -0.012668  0.012687 ) ph/cm2/s
Energy fluence (15-150 keV)             : 6.08492e-06 ( -3.30707e-07  3.2874e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   21.620 sec. to   22.620 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.40468     ( -0.182125   0.179708 )
Norm@50keV  : 2.42206E-02    ( -0.00275519   0.00274811 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   67.27     using 59 bins.
 Reduced chi-squared = 1.18018
# Null hypothesis probability of 1.66e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.95282 ( -0.33728  0.33776 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.33841e-07 ( -2.90598e-08  2.92767e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   21.620 sec. to   22.620 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.304777     ( -0.814139   0.990356 )
Epeak [keV] : 80.1835      ( -17.7422 78.3497 )
Norm@50keV  : 8.36385E-02    ( -0.0495064   0.162849 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   61.69     using 59 bins.
 Reduced chi-squared = 1.10161
# Null hypothesis probability of 2.80e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.84601 ( -0.34825  0.34772 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.21335e-07 ( -3.10432e-08  3.12456e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 258.032 sec.
Hardness ratio (energy fluence ratio) = 1.30214682309

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

S(15-50 keV)  = 2.564718e-06
S(50-150 keV) = 3.622915e-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 = -4.616012525820294E-01, IMY = -5.295442998562524E-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:
-239.600000 -19.224000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
135.5729 -40.5623    2.0  27.8 -126.6   2.4990   5.7    2.1	Vela X-1                      
162.3501  -4.2314    2.6  33.6  140.5   2.1437   4.5 ------	UNKNOWN                       
120.5214  12.0312    2.3  26.9   43.2   2.0782   5.1 ------	UNKNOWN                       
 72.9554 -11.9610    2.1  55.2  -32.3   9.5929   5.4 ------	UNKNOWN                       

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

Time interval of the image:
-19.224000 10.500600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
135.6052 -40.4985    2.3  27.7 -126.7  -0.4436  -4.9    4.9	Vela X-1                      
161.8058   1.2898    0.5  35.1  131.1   3.5811  23.8 ------	UNKNOWN                       
185.1200 -40.2664    2.4  55.3 -166.7   1.2905   4.8 ------	UNKNOWN                       
 83.6861 -25.7293    3.0  44.8  -50.1   0.8645   3.8 ------	UNKNOWN                       
 87.5457 -34.8657    3.5  43.6  -64.0   1.0093   3.3 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
135.700600 962.531000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
135.4644 -40.5653    2.2  48.2  -18.2  11.4727   5.1    3.0	Vela X-1                      
114.1203  -7.3832    2.7  48.3   34.0  13.7710   4.3 ------	UNKNOWN                       
134.8704   0.2953    2.4  26.9   43.2   7.3599   4.7 ------	UNKNOWN                       
171.3141  11.7770    2.6  14.2  176.7   4.9383   4.4 ------	UNKNOWN                       
134.8755 -27.5431    3.2  38.7   -5.1   6.0225   3.6 ------	UNKNOWN                       
213.8744  30.3303    2.3  57.3 -170.9  23.8232   5.0 ------	UNKNOWN                       
174.3628 -42.9453    2.7  45.6  -57.9  23.9098   4.3 ------	UNKNOWN