GRB250221A

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: Fri Jun 20 17:29:13 EDT 2025
             Host Name: batproc1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger1290305
======================================================================

  Trigger: 01290305      Segment: 000

  BAT Trigger Time: 761801712.192   [s; MET]
      Trigger Stop: 761801714.24   [s; MET]
               UTC: 2025-02-21T03:34:37.076040    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 59.4766170518887   Dec: -15.1387040573162  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    10.54
     Image Trigger?:     NO
     Rate S/N Ratio:     22.7156333832011  [ if not an image trigger ]
     Image S/N Ratio:    10.54

  Analysis Position:   [ source = BAT ]
    RA: 59.4766170518887   Dec: -15.1387040573162  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 59.4757486909577   Dec: -15.135824739688  [deg; J2000]  
        { 03h 57m 54.2s , -15d 08' 09.0" }
         +/- 1.87833796411089 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.811285701197408 [arcmin] (formal 1-sigma fit error)
    SNR: 12.3598455084786
 
  Angular difference between the analysis and refined position is 0.179931 arcmin
 
  Partial Coding Fraction: 0.1972656    [ including projection effects ]

  Duration
     T90: 1.79999995231628 +/- 0.30841529631772
        Measured from: -0.136000037193298
                   to: 1.66399991512299     [s; relative to TRIGTIME]
     T50: 0.879999876022339 +/- 0.235185044842754
        Measured from: 0.351999998092651
                   to: 1.23199987411499     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 0.424000024795532     
                   to: 1.42400002479553     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -0.220000028610229     
                   to: 1.84399998188019     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.143534   0.202021   0.196426   0.044810
           0.024026   0.027180   0.024398   0.020026 [error]
 Peak      0.080075   0.112870   0.138871   0.019229
           0.016928   0.019597   0.018122   0.013810 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100    2.064   -0.220    1.844
T90     1.800   -0.136    1.664
T50     0.880    0.352    1.232
Peak    1.000    0.424    1.424
 
 
====== 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      -1.418    -0.230      0.229       -           -               -         2.00e-02     -2.66e-03          2.66e-03      45.640   57
CPL     -1.273    -1.363      0.997      260.707    -260.707      -260.707      2.36e-02     -1.95e-02          4.58e-02      45.570   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      -1.337     -0.260     0.258       -           -               -         2.41e-02     -3.90e-03          3.89e-03      50.680   57
CPL      0.051     -1.181     1.669       84.790     -19.618       135.050      9.99e-02     -9.99e-02          3.52e-01      46.500   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   4.88e-08  9.43e-08  1.41e-07  4.57e-07  3.98e-07  7.41e-07   erg/cm2
      90%_error_low -1.10e-08 -1.35e-08 -2.38e-08 -1.47e-07 -5.79e-08 -1.67e-07   erg/cm2
      90%_error_hi   1.17e-08  1.33e-08  2.35e-08  1.86e-07  5.84e-08  1.99e-07   erg/cm2
Peak flux       PL   8.49e-01  9.41e-01  7.45e-01  9.75e-01  2.90e+00  3.51e+00   ph/cm2/s
      90%_error_low -2.30e-01 -1.72e-01 -1.41e-01 -3.26e-01 -4.81e-01 -5.77e-01   ph/cm2/s
      90%_error_hi   2.51e-01  1.69e-01  1.39e-01  4.04e-01  4.83e-01  5.82e-01   ph/cm2/s
 
Fluence        CPL   4.75e-08  9.57e-08  1.43e-07  3.70e-07  3.95e-07  6.56e-07   erg/cm2
      90%_error_low -1.36e-08 -1.46e-08 -2.54e-08 -2.54e-07 -6.15e-08 -2.61e-07   erg/cm2
      90%_error_hi   1.13e-08  1.62e-08  2.71e-08  1.23e-07  5.96e-08  1.39e-07   erg/cm2
Peak flux      CPL   5.88e-01  1.01e+00  8.78e-01  3.86e-01  2.74e+00  2.86e+00   ph/cm2/s
      90%_error_low -2.99e-01 -2.04e-01 -1.84e-01 -2.10e-01 -5.11e-01 -5.75e-01   ph/cm2/s
      90%_error_hi   3.27e-01  2.03e-01  1.95e-01  4.64e-01  5.06e-01  6.58e-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
   59.4757   -15.1358   0.0156    40.2471   -59.5840         0.6253832     12.360 TRIG_01290305                 
 
Foreground time interval of the image:
 -0.220   1.844 (delta_t =   2.064 [sec])
Background time interval of the image:
-194.491  -0.220 (delta_t = 194.271 [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:

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   -0.220 sec. to    1.844 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.41801     ( -0.22981   0.229011 )
Norm@50keV  : 2.00056E-02    ( -0.00266355   0.00265496 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   45.64     using 59 bins.
 Reduced chi-squared = 0.800702
# Null hypothesis probability of 8.60e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 2.064 sec: 2.44650 ( -0.33155  0.33247 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.97595e-07 ( -5.79303e-08  5.8379e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from   -0.220 sec. to    1.844 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.27291     ( -1.36152   0.998392 )
Epeak [keV] : 260.707      ( -266.328 -266.328 )
Norm@50keV  : 2.35518E-02    ( -0.0194291   0.0458727 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   45.57     using 59 bins.
 Reduced chi-squared = 0.81375
# Null hypothesis probability of 8.39e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 2.064 sec: 2.43319 ( -0.3423  0.33308 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.94511e-07 ( -6.14989e-08  5.96395e-08 ) ergs/cm2

1-s peak spectrum fit

Power-law model

Time interval is from    0.424 sec. to    1.424 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.33719     ( -0.260136   0.257948 )
Norm@50keV  : 2.41030E-02    ( -0.0039001   0.00389427 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   50.68     using 59 bins.
 Reduced chi-squared = 0.889123
# Null hypothesis probability of 7.10e-01 with 57 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.89622 ( -0.48126  0.48291 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.36118e-07 ( -4.12009e-08  4.15015e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from    0.424 sec. to    1.424 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 0.0513541     ( -1.18114   1.66889 )
Epeak [keV] : 84.7899      ( -19.6206 135.047 )
Norm@50keV  : 9.98790E-02    ( -0.0998791   0.351531 )
------------------------------------------------------------
#Fit statistic  : Chi-Squared                   46.50     using 59 bins.
 Reduced chi-squared = 0.830357
# Null hypothesis probability of 8.13e-01 with 56 degrees of freedom
 
Photon flux (15-150 keV)    in 1 sec: 2.74153 ( -0.51078  0.50578 ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.49415e-08 ( -4.40135e-08  1.71666e-08 ) ergs/cm2

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 1.8 sec.
Hardness ratio (energy fluence ratio) = 1.49695960672

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

S(15-50 keV)  = 1.4316343e-07
S(50-150 keV) = 2.544344e-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 = 4.285496407615806E-01, IMY = 7.299776838040873E-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:
-194.491400 -0.220000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6311  22.0258    0.8  43.8    8.4   6.8711  13.9    0.7	Crab                          
135.5592 -40.6044    2.5  36.8  167.3   1.8880   4.5    3.3	Vela X-1                      
154.1997 -62.0998    2.3  57.0 -173.8   5.7641   5.0 ------	UNKNOWN                       
 61.7114 -42.5922    2.3  41.5 -102.2   6.9574   5.0 ------	UNKNOWN

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

Time interval of the image:
-0.220000 1.844000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6753  21.9164    3.7  43.7    8.3   0.0982   3.1    6.3	Crab                          
135.2866 -40.5495    0.0  36.6  167.4  -0.0341  -1.4   11.0	Vela X-1                      
133.9363 -66.4516    2.6  52.7 -163.1   0.2456   4.5 ------	UNKNOWN                       
 59.4758 -15.1358    0.9  40.2  -59.6   0.6254  12.4 ------	UNKNOWN

Post-slew image of 15-350 keV band

Time interval of the image:
105.908580 903.048000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6382  22.0310    0.9  44.1   42.1  19.3005  13.3    1.0	Crab                          
 88.1215 -65.6299    2.5  54.0  174.9   9.8678   4.6 ------	UNKNOWN                       
 16.4254 -25.2517    3.1  41.5 -102.1  12.3747   3.7 ------	UNKNOWN

Analysis Summary

Notes:

Image

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

Light Curves

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:

Time averaged spectrum fit using the average DRM

Power-law model

Cutoff power-law model

1-s peak spectrum fit

Power-law model

Cutoff power-law model

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

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

Mask shadow pattern

Spacecraft aspect plot

Bright source in the pre-burst/pre-slew/post-slew images

Pre-burst image of 15-350 keV band

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

Post-slew image of 15-350 keV band

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