GRB250128B: 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 21:43:19 EDT 2025
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1285677
======================================================================

  Trigger: 01285677      Segment: 000

  BAT Trigger Time: 759774208.696   [s; MET]
      Trigger Stop: 759774208.76   [s; MET]
               UTC: 2025-01-28T16:22:53.718560    [includes UTCF correction] 
       Where From?: (*SHORT BURST*) TDRSS scaled map message

  BAT 
    RA: 231.419897727353   Dec: -0.517133136897832  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    7.64
     Image Trigger?:     NO
     Rate S/N Ratio:     24.7588368062799  [ if not an image trigger ]
     Image S/N Ratio:    7.64

  Analysis Position:   [ source = BAT ]
    RA: 231.419897727353   Dec: -0.517133136897832  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 231.422941890195   Dec: -0.546452473321537  [deg; J2000]  
        { 15h 25m 41.5s , -00d 32' 47.2" }
         +/- 2.03249281623113 [arcmin] (estimated 90% radius based on SNR)
         +/- 1.02758498431348 [arcmin] (formal 1-sigma fit error)
    SNR: 11.0427419581179
 
  Angular difference between the analysis and refined position is 1.768616 arcmin
 
  Partial Coding Fraction: 1.015625    [ including projection effects ]

  Duration
     T90: 0.483999967575073 +/- 0.109836277653587
        Measured from: -0.0119999647140503
                   to: 0.472000002861023     [s; relative to TRIGTIME]
     T50: 0.192000031471252 +/- 0.137462638301169
        Measured from: 0.0199999809265137
                   to: 0.212000012397766     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: -0.22599995136261     
                   to: 0.77400004863739     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -0.0199999809265137     
                   to: 0.564000010490417     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.023608   0.035595   0.030546   0.018368
           0.005253   0.005305   0.004775   0.003654 [error]
 Peak      0.019050   0.030501   0.029422   0.011901
           0.006533   0.006612   0.005682   0.004625 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100    0.584   -0.020    0.564
T90     0.484   -0.012    0.472
T50     0.192    0.020    0.212
Peak    1.000   -0.226    0.774
 
 
====== 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      -1.303    -0.275      0.273       -           -               -         1.14e-02     -1.73e-03          1.72e-03      54.130   57
CPL     -1.301    -0.273      0.430     9999.280    -9999.280      -9999.280      1.14e-02     -1.73e-03          2.12e-02      54.130   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      -1.248     -0.375     0.381       -           -               -         5.88e-03     -1.22e-03          1.22e-03      65.640   57
CPL     -1.046     -1.555     1.780      259.668      N/A           N/A         7.22e-03        N/A               N/A         65.630   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   7.06e-09  1.46e-08  2.37e-08  8.64e-08  6.57e-08  1.32e-07   erg/cm2
      90%_error_low -1.90e-09 -2.48e-09 -4.55e-09 -3.17e-08 -1.11e-08 -3.55e-08   erg/cm2
      90%_error_hi   2.07e-09  2.43e-09  4.45e-09  4.21e-08  1.12e-08  4.41e-08   erg/cm2
Peak flux       PL   1.90e-01  2.22e-01  1.87e-01  2.67e-01  6.95e-01  8.66e-01   ph/cm2/s
      90%_error_low -7.23e-02 -5.59e-02 -4.61e-02 -1.17e-01 -1.50e-01 -1.86e-01   ph/cm2/s
      90%_error_hi   8.27e-02  5.41e-02  4.48e-02  1.63e-01  1.51e-01  1.90e-01   ph/cm2/s
 
Fluence        CPL   7.17e-09  1.46e-08  2.37e-08  8.83e-08  6.58e-08  1.24e-07   erg/cm2
      90%_error_low -1.32e-09 -2.45e-09 -4.48e-09 -6.50e-08 -1.15e-08 -5.45e-08   erg/cm2
      90%_error_hi   1.96e-09  2.76e-09  5.20e-09  4.16e-08  9.60e-09  4.99e-08   erg/cm2
Peak flux      CPL   1.83e-01  2.24e-01  1.91e-01  2.30e-01  6.90e-01  8.28e-01   ph/cm2/s
      90%_error_low -1.83e-01 -5.72e-02 -4.89e-02 -2.30e-01 -1.58e-01 -2.60e-01   ph/cm2/s
      90%_error_hi   8.79e-02  6.03e-02  5.79e-02  1.74e-01  1.55e-01  2.24e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  231.4229    -0.5465   0.0175    18.2395   -15.6573         0.1071848     11.043 TRIG_01285677                 
 
Foreground time interval of the image:
 -0.020   0.564 (delta_t =   0.584 [sec])
Background time interval of the image:
-239.696  -0.020 (delta_t = 239.676 [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   -0.020 sec. to    0.564 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.30271     ( -0.274668   0.272629 )
Norm@50keV  : 1.13863E-02    ( -0.0017251   0.00172233 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   54.13     using 59 bins.
 Reduced chi-squared = 0.949649
# Null hypothesis probability of 5.83e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 0.584 sec: 1.35912 ( -0.21049  0.21108 ) ph/cm2/s
Energy fluence (15-150 keV)             : 6.56737e-08 ( -1.11265e-08  1.12275e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.020 sec. to    0.564 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.30143     ( -0.274201   0.429267 )
Epeak [keV] : 9999.28      ( -9999.36 -9999.36 )
Norm@50keV  : 1.14248E-02    ( -0.00173417   0.0212233 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   54.13     using 59 bins.
 Reduced chi-squared = 0.966607
# Null hypothesis probability of 5.46e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 0.584 sec: 1.35890 ( -0.21048  0.21092 ) ph/cm2/s
Energy fluence (15-150 keV)             : 6.57584e-08 ( -1.15454e-08  9.59845e-09 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from   -0.226 sec. to    0.774 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.24759     ( -0.375283   0.381345 )
Norm@50keV  : 5.87643E-03    ( -0.00122446   0.00122444 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   65.64     using 59 bins.
 Reduced chi-squared = 1.15158
# Null hypothesis probability of 2.02e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 0.694757 ( -0.150371  0.151285 ) ph/cm2/s
Energy fluence (15-150 keV)             : 5.88545e-08 ( -1.34342e-08  1.35607e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -0.226 sec. to    0.774 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -2.48973     ( -0.111546   3.22277 )
Epeak [keV] : 159.304      (   )
Norm@50keV  : 1.27274E-03    (     )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   65.58     using 59 bins.
 Reduced chi-squared = 1.17107
# Null hypothesis probability of 1.79e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 0.690232 ( -0.158075  0.154661 ) ph/cm2/s
Energy fluence (15-150 keV)             : 5.85113e-08 ( -1.4041e-08  1.37956e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 0.484 sec.
Hardness ratio (energy fluence ratio) = 1.62151188684

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

S(15-50 keV)  = 2.1699363e-08
S(50-150 keV) = 4.397486e-08

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 = 3.173179519661429E-01, IMY = 8.893923559529868E-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:
-239.696000 -0.020000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
244.9653 -15.6139    0.7  35.9  -38.3   7.4206  16.1    1.8	Sco X-1                       
254.4526  35.3770    2.0  27.0 -151.1   2.1396   5.9    2.1	Her X-1                       
190.4125  41.7204    2.8  42.4  117.7   8.1128   4.1 ------	UNKNOWN                       
208.6265  13.2670    2.6  22.4   66.1   1.6731   4.5 ------	UNKNOWN                       
211.2108  10.6144    2.8  20.8   57.1   1.4870   4.1 ------	UNKNOWN                       
211.1897 -18.6552    2.7  41.4   14.0   2.4152   4.3 ------	UNKNOWN                       
266.0223   0.7583    2.6  38.0  -83.0   4.1684   4.5 ------	UNKNOWN                       

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

Time interval of the image:
-0.020000 0.564000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
244.9728 -15.5537    5.0  35.8  -38.4  -0.0308  -2.3    5.2	Sco X-1                       
254.5484  35.1666    4.1  27.0 -150.7  -0.0286  -2.8   11.5	Her X-1                       
231.4230  -0.5465    1.0  18.2  -15.7   0.1072  11.0 ------	UNKNOWN                       
224.3981 -39.6229    2.3  57.7   -9.3   0.2446   5.1 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
61.804600 962.343900
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
244.9698 -15.6420    0.6  20.2  -58.9  28.3538  20.2    0.6	Sco X-1                       
254.4155  35.3876    5.7  41.8 -169.5   3.8080   2.0    3.4	Her X-1                       
255.7991 -37.9715    7.3  43.6  -46.1   4.8879   1.6   11.7	4U 1700-377                   
256.3950 -36.5521    9.9  42.8  -47.9   3.2943   1.2    8.0	GX 349+2                      
263.1782 -24.7344   87.8  39.1  -67.3  -0.3900  -0.1    9.2	GX 1+4                        
268.4963  -1.5489   15.0  37.1 -106.1   2.4761   0.8    9.6	SW J1753.5-0127               
262.9341 -33.8593   64.9  44.5  -56.3  -0.8567  -0.2    3.1	GX 354-0                      
199.0337  28.3517    2.6  42.4  117.6  32.8256   4.5 ------	UNKNOWN                       
201.6871  -1.8943    3.0  29.7   69.1   8.4220   3.8 ------	UNKNOWN                       
223.3815 -51.9339    2.5  51.8  -11.7  11.5457   4.6 ------	UNKNOWN                       
227.8000 -56.1899    2.1  55.7  -15.6  16.6849   5.5 ------	UNKNOWN