GRB241228A: 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: Thu Jun 19 22:01:23 EDT 2025
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1277277
======================================================================

  Trigger: 01277277      Segment: 000

  BAT Trigger Time: 757051069.952   [s; MET]
      Trigger Stop: 757051070.464   [s; MET]
               UTC: 2024-12-28T03:57:15.160580    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 344.824008424848   Dec: 18.6040815474546  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    20.9
     Image Trigger?:     NO
     Rate S/N Ratio:     97.1699542039616  [ if not an image trigger ]
     Image S/N Ratio:    20.9

  Analysis Position:   [ source = BAT ]
    RA: 344.824008424848   Dec: 18.6040815474546  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 344.810542193093   Dec: 18.6078539635926  [deg; J2000]  
        { 22h 59m 14.5s , +18d 36' 28.3" }
         +/- 0.759889074371972 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.278990577965484 [arcmin] (formal 1-sigma fit error)
    SNR: 45.0272306205382
 
  Angular difference between the analysis and refined position is 0.798497 arcmin
 
  Partial Coding Fraction: 0.390625    [ including projection effects ]

  Duration
     T90: 8.067999958992 +/- 0.53329541361275
        Measured from: -4.34399998188019
                   to: 3.72399997711182     [s; relative to TRIGTIME]
     T50: 2.55200004577637 +/- 0.0699713805412762
        Measured from: 0.107999920845032
                   to: 2.6599999666214     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 1.94400000572205     
                   to: 2.94400000572205     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -5.1599999666214     
                   to: 4.77999997138977     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     1.465166   2.230185   1.291613   0.214324
           0.042622   0.048173   0.039448   0.025374 [error]
 Peak      0.368810   0.700469   0.461953   0.064053
           0.018609   0.023152   0.019276   0.009962 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100    9.940   -5.160    4.780
T90     8.068   -4.344    3.724
T50     2.552    0.108    2.660
Peak    1.000    1.944    2.944
 
 
====== 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: 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      -1.799     N/A       N/A          -           -               -         3.45e-02        N/A               N/A        115.190   57
CPL     -0.946    -0.237      0.250       61.704      -4.657         6.501      9.22e-02     -2.16e-02          3.03e-02      72.080   56
 
 
=== 1-s peak spectral analysis ===
(Best model with acceptable fit: CPL)
 
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      -1.591      N/A       N/A          -           -               -         1.05e-01        N/A               N/A        131.340   57
CPL     -0.175     -0.321     0.345       64.310      -4.558         5.935      5.55e-01     -1.71e-01          2.71e-01      60.980   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   5.80e-07  8.88e-07  1.02e-06  2.25e-06  3.16e-06  4.74e-06   erg/cm2
      90%_error_low    N/A       N/A       N/A       N/A       N/A       N/A      erg/cm2
      90%_error_hi     N/A       N/A       N/A       N/A       N/A       N/A      erg/cm2
Peak flux       PL   4.72e+00  4.50e+00  2.98e+00  3.08e+00  1.35e+01  1.53e+01   ph/cm2/s
      90%_error_low     N/A       N/A       N/A       N/A       N/A       N/A     ph/cm2/s
      90%_error_hi      N/A       N/A       N/A       N/A       N/A       N/A     ph/cm2/s
 
Fluence        CPL   4.97e-07  9.57e-07  1.07e-06  8.14e-07  2.99e-06  3.34e-06   erg/cm2
      90%_error_low -3.53e-08 -3.41e-08 -4.49e-08 -1.76e-07 -1.07e-07 -2.04e-07   erg/cm2
      90%_error_hi   3.59e-08  3.44e-08  4.51e-08  2.30e-07  1.07e-07  2.47e-07   erg/cm2
Peak flux      CPL   3.73e+00  5.20e+00  3.40e+00  9.68e-01  1.31e+01  1.33e+01   ph/cm2/s
      90%_error_low -3.65e-01 -2.61e-01 -1.89e-01 -2.16e-01 -5.88e-01 -6.24e-01   ph/cm2/s
      90%_error_hi   3.72e-01  2.65e-01  1.91e-01  2.62e-01  5.89e-01  6.31e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  344.8105    18.6079   0.0043    32.4074  -114.4663         5.5217561     45.027 TRIG_01277277                 
 
Foreground time interval of the image:
 -5.160   4.780 (delta_t =   9.940 [sec])
Background time interval of the image:
-64.051  -5.160 (delta_t =  58.891 [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   -5.160 sec. to    4.780 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.79891     (       )
Norm@50keV  : 3.44806E-02    (     )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                  115.19     using 59 bins.
 Reduced chi-squared = 2.02088
# Null hypothesis probability of 8.11e-06 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 9.94 sec: 4.74961 (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.15585e-06 ( 0  0 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -5.160 sec. to    4.780 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.946135     ( -0.236668   0.250039 )
Epeak [keV] : 61.7042      ( -4.65677 6.50135 )
Norm@50keV  : 9.21794E-02    ( -0.0216196   0.0302628 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   72.08     using 59 bins.
 Reduced chi-squared = 1.28714
# Null hypothesis probability of 7.27e-02 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 9.94 sec: 4.52746 ( -0.16192  0.16249 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.99292e-06 ( -1.06857e-07  1.06896e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from    1.944 sec. to    2.944 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.5915     (       )
Norm@50keV  : 0.104953    (     )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                  131.34     using 59 bins.
 Reduced chi-squared = 2.30421
# Null hypothesis probability of 8.44e-08 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 13.4522 (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 9.82698e-07 ( 0  0 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    1.944 sec. to    2.944 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.175162     ( -0.320626   0.344542 )
Epeak [keV] : 64.3101      ( -4.55824 5.93546 )
Norm@50keV  : 0.555414    ( -0.171208   0.270796 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   60.98     using 59 bins.
 Reduced chi-squared = 1.08893
# Null hypothesis probability of 3.02e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 13.0786 ( -0.5883  0.5888 ) ph/cm2/s
Energy fluence (15-150 keV)             : 9.33577e-07 ( -4.5624e-08  4.57777e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = N/A sec.
Hardness ratio (energy fluence ratio) = N/A

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

S(15-50 keV)  = N/A
S(50-150 keV) = N/A

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 = -2.629074649383593E-01, IMY = 5.777981538541936E-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:
-64.051400 -5.160000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
308.0532  40.8930   54.1  46.3  -55.5   0.1118   0.2    4.4	Cyg X-3                       
326.2993  38.2597    4.6  34.2  -67.4   0.4659   2.5    7.1	Cyg X-2                       
 31.2429 -10.1488    2.3  55.2  169.3   2.5401   5.1 ------	UNKNOWN                       
 23.6546  -1.6784    2.6  45.0  175.9   1.0054   4.5 ------	UNKNOWN                       
340.7708  27.1099    2.0  29.0  -97.5   0.9015   5.9 ------	UNKNOWN                       
303.6291  50.0129    2.3  46.1  -42.2   1.4561   5.0 ------	UNKNOWN                       

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

Time interval of the image:
-5.160000 4.780000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
308.1742  40.8368    4.0  46.3  -55.6  -1.0606  -2.9    7.5	Cyg X-3                       
326.0624  38.2186   11.6  34.4  -67.3   0.1233   1.0    8.0	Cyg X-2                       
 27.8978  -1.2692    4.2  45.7  170.0   0.3163   2.7 ------	UNKNOWN                       
249.9007  73.6052    2.3  57.9   -3.1   1.6690   5.0 ------	UNKNOWN                       
 16.6142  -5.4363    3.1  47.6 -173.7   0.4461   3.7 ------	UNKNOWN                       
  9.7332  19.7285    2.8  22.2 -162.6   0.2590   4.1 ------	UNKNOWN                       
316.4344  63.4921    2.1  37.9  -23.0   0.5352   5.5 ------	UNKNOWN                       
344.8105  18.6079    0.3  32.4 -114.5   5.5218  45.0 ------	UNKNOWN                       
339.0840  22.9471    2.8  32.8 -101.7   0.5732   4.1 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
80.148610 104.028000
105.048000 1101.188000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
299.5773  35.2440    1.5  43.2  -27.8  16.5587   7.5    2.6	Cyg X-1                       
308.0852  40.8632    5.7  38.4  -16.6   3.7314   2.0    5.5	Cyg X-3                       
326.1119  38.1631   11.2  25.4   -5.8   1.3851   1.0    9.9	Cyg X-2                       
334.6952   6.5172    2.5  15.6 -109.4   5.9035   4.7 ------	UNKNOWN                       
  2.5622 -37.8302    3.0  58.9 -166.2  29.6268   3.9 ------	UNKNOWN                       
319.8246   8.6475    2.9  26.2  -78.9   6.3787   4.1 ------	UNKNOWN                       
311.8151   6.1047    2.5  34.5  -76.9  10.9204   4.7 ------	UNKNOWN