GRB180828A

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 v2.46
    Process Start Time: Fri Oct 19 18:24:11 EDT 2018
             Host Name: bat1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger856977
======================================================================

  Trigger: 00856977      Segment: 000

  BAT Trigger Time: 557175476.288   [s; MET]
      Trigger Stop: 557175477.312   [s; MET]
               UTC: 2018-08-28T18:57:34.785720    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 268.699972359996   Dec: -25.7997839712606  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    16.5
     Image Trigger?:     NO
     Rate S/N Ratio:     120.685541801825  [ if not an image trigger ]
     Image S/N Ratio:    16.5

  Analysis Position:   [ source = BAT ]
    RA: 268.699972359996   Dec: -25.7997839712606  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 268.704088873397   Dec: -25.7914707658866  [deg; J2000]  
        { 17h 54m 49.0s , -25d 47' 29.3" }
         +/- 0.85469475352285 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.400414649069615 [arcmin] (formal 1-sigma fit error)
    SNR: 38.0654687959079
 
  Angular difference between the analysis and refined position is 0.546119 arcmin
 
  Partial Coding Fraction: 0.1855469    [ including projection effects ]

  Duration
     T90: 13 +/- 9
        Measured from: -7.28799998760223
                   to: 5.71200001239777     [s; relative to TRIGTIME]
     T50: 4 +/- 1
        Measured from: -4.28799998760223
                   to: -0.287999987602234     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: -0.287999987602234     
                   to: 0.712000012397766     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -7.28799998760223     
                   to: 28.7120000123978     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     1.477350   3.076445   4.237919   2.250834
           0.102280   0.114736   0.115899   0.106811 [error]
 Peak      0.232381   0.573992   0.968137   0.544185
           0.024027   0.032463   0.040298   0.036794 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   36.000   -7.288   28.712
T90    13.000   -7.288    5.712
T50     4.000   -4.288   -0.288
Peak    1.000   -0.288    0.712
 
 
====== 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      -0.891    -0.062      0.063       -           -               -         2.17e-02     -8.17e-04          8.11e-04      46.330   57
CPL     -0.795    -0.119      0.255      833.089    -833.089      -833.089      2.36e-02     -1.14e-03          5.72e-03      45.890   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      -0.634     -0.089     0.091       -           -               -         1.53e-01     -8.59e-03          8.50e-03      49.190   57
CPL     -0.509     -0.160     0.378      797.267    -797.267      -797.267      1.71e-01     -3.33e-02          6.51e-02      48.840   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   5.65e-07  1.51e-06  3.26e-06  1.83e-05  8.79e-06  2.36e-05   erg/cm2
      90%_error_low -4.59e-08 -7.49e-08 -1.09e-07 -1.43e-06 -2.95e-07 -1.45e-06   erg/cm2
      90%_error_hi   4.75e-08  7.46e-08  1.09e-07  1.52e-06  2.95e-07  1.52e-06   erg/cm2
Peak flux       PL   2.77e+00  4.69e+00  6.05e+00  1.57e+01  1.78e+01  2.92e+01   ph/cm2/s
      90%_error_low -3.26e-01 -3.50e-01 -3.00e-01 -1.63e+00 -9.25e-01 -1.71e+00   ph/cm2/s
      90%_error_hi   3.43e-01  3.49e-01  2.99e-01  1.76e+00  9.25e-01  1.76e+00   ph/cm2/s
 
Fluence        CPL   5.46e-07  1.51e-06  3.30e-06  1.65e-05  8.78e-06  2.19e-05   erg/cm2
      90%_error_low -6.36e-08 -7.57e-08 -7.42e-08 -3.78e-06 -2.97e-07 -3.74e-06   erg/cm2
      90%_error_hi   5.59e-08  7.56e-08  1.50e-07  2.56e-06  2.96e-07  1.21e-06   erg/cm2
Peak flux      CPL   2.65e+00  4.69e+00  6.16e+00  1.41e+01  1.78e+01  2.76e+01   ph/cm2/s
      90%_error_low -4.53e-01 -3.56e-01 -3.87e-01 -3.64e+00 -9.31e-01 -3.73e+00   ph/cm2/s
      90%_error_hi   3.88e-01  3.54e-01  4.36e-01  2.54e+00  9.28e-01  2.34e+00   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
  268.7041   -25.7915   0.0051    53.3691    -7.3856        11.3635578     38.065 TRIG_00856977                 
 
Foreground time interval of the image:
 -7.288  16.013 (delta_t =  23.301 [sec])
Background time interval of the image:
-239.288  -7.288 (delta_t = 232.000 [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   -7.288 sec. to   28.712 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.890869     ( -0.0620739   0.0630345 )
Norm@50keV  : 2.16686E-02    ( -0.000816866   0.000810974 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          46.33 using 59 PHA bins.
# Reduced chi-squared =         0.8128 for     57 degrees of freedom 
# Null hypothesis probability =   8.427770e-01
 
Photon flux (15-150 keV)    in 36 sec: 2.48691 ( -0.09358  0.09404 ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.78663e-06 ( -2.9497e-07  2.94975e-07 ) ergs/cm2

Cutoff power-law model

Time interval is from   -7.288 sec. to   28.712 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.795173     ( -0.118546   0.254798 )
Epeak [keV] : 833.089      ( -833.089 -833.089 )
Norm@50keV  : 2.35697E-02    ( -0.00113673   0.00572401 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          45.89 using 59 PHA bins.
# Reduced chi-squared =         0.8194 for     56 degrees of freedom 
# Null hypothesis probability =   8.304687e-01
 
Photon flux (15-150 keV)    in 36 sec: 2.47504 ( -0.09782  0.08829 ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.77673e-06 ( -2.96793e-07  2.96305e-07 ) ergs/cm2

1-s peak spectrum fit

Power-law model

Time interval is from   -0.288 sec. to    0.712 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.633652     ( -0.0886879   0.0907421 )
Norm@50keV  : 0.153240    ( -0.00858942   0.00849813 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          49.19 using 59 PHA bins.
# Reduced chi-squared =         0.8630 for     57 degrees of freedom 
# Null hypothesis probability =   7.593980e-01
 
Photon flux (15-150 keV)    in 1 sec: 17.8227 ( -0.9245  0.9254 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.92872e-06 ( -9.9525e-08  9.96165e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from   -0.288 sec. to    0.712 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.508824     ( -0.159509   0.378072 )
Epeak [keV] : 797.267      ( -797.267 -797.267 )
Norm@50keV  : 0.171104    ( -0.0332553   0.0651473 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          48.84 using 59 PHA bins.
# Reduced chi-squared =         0.8721 for     56 degrees of freedom 
# Null hypothesis probability =   7.403182e-01
 
Photon flux (15-150 keV)    in 1 sec: 17.7794 ( -0.9309  0.9282 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.92983e-06 ( -9.99189e-08  1.00048e-07 ) ergs/cm2

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 13.0 sec.
Hardness ratio (energy fluence ratio) = 2.15714874663

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

S(15-50 keV)  = 2.0760423e-06
S(50-150 keV) = 6.710554e-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 = 1.333826326491719E+00, IMY = 1.728940634877155E-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:
-239.288000 -7.288000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
262.9703 -24.7811   25.9  58.6   -8.5   0.5864   0.4    3.0	GX 1+4                        
264.6837 -44.5762    9.9  52.1  -31.3   0.8048   1.2    8.0	4U 1735-44                    
270.4582 -25.0619    6.1  52.1   -5.8   1.0904   1.9    9.5	GX 5-1                        
270.3855 -25.7612   17.1  52.0   -6.7  -0.3772  -0.7    4.6	GRS 1758-258                  
274.0130 -14.0310   78.2  53.5    8.5  -0.1216  -0.1    0.5	GX 17+2                       
276.0176 -30.4123    7.2  45.8  -10.7   0.7270   1.6    5.5	H1820-303                     
285.0359 -24.9249   26.1  39.7    0.3   0.1702   0.4    0.3	HT1900.1-2455                 
262.9961 -33.9781   10.4  55.6  -18.8  -0.8698  -1.1    8.6	GX 354-0                      
 26.2217  -8.7497    2.8  56.8  174.0   5.1419   4.1 ------	UNKNOWN                       
271.7807 -19.3274    2.4  53.1    1.4   3.0754   4.7 ------	UNKNOWN                       
350.9705 -52.5631    2.4  27.2 -115.1   1.4176   4.8 ------	UNKNOWN                       
337.6478 -54.9427    2.5  25.3  -96.9   1.3705   4.7 ------	UNKNOWN                       
 22.4457 -58.7385    3.7  45.4 -121.6   3.2723   3.2 ------	UNKNOWN                       
 28.9297 -53.6645    3.2  48.1 -129.3   3.8732   3.7 ------	UNKNOWN

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

Time interval of the image:
-7.288000 16.012590
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
262.9893 -24.7884    3.9  58.6   -8.5  -2.0057  -2.9    2.8	GX 1+4                        
264.8863 -44.4013    8.1  52.0  -31.1   0.3810   1.4    6.8	4U 1735-44                    
270.2675 -25.0726  118.7  52.3   -5.9   0.0258   0.1    1.0	GX 5-1                        
270.2992 -25.7448   22.4  52.0   -6.7   0.1391   0.5    0.2	GRS 1758-258                  
273.9979 -13.9411    7.4  53.5    8.6   0.6991   1.6    5.7	GX 17+2                       
275.7489 -30.4030    5.5  46.1  -10.8  -0.3627  -2.1    9.4	H1820-303                     
285.1119 -24.8212    5.1  39.6    0.5   0.2922   2.2    7.3	HT1900.1-2455                 
263.0322 -33.7534    7.1  55.6  -18.6   0.5972   1.6    5.3	GX 354-0                      
268.7039 -25.7915    0.3  53.4   -7.4  11.3476  37.7 ------	UNKNOWN                       
268.8633 -26.8194    2.7  52.9   -8.5   1.2800   4.3 ------	UNKNOWN                       
  3.3707 -49.3693    1.8  31.8 -129.5   0.6712   6.5 ------	UNKNOWN                       
 37.1101 -32.0538    2.3  56.8 -155.6   2.1745   5.1 ------	UNKNOWN

Post-slew image of 15-350 keV band

Time interval of the image:
103.812590 155.012610
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
244.9742 -15.6201    0.6  24.4  -69.3   2.2465  19.4    1.2	Sco X-1                       
255.9703 -37.8760   11.3  16.2 -140.6   0.1002   1.0    2.1	4U 1700-377                   
256.2565 -36.4406  257.3  15.1 -137.3   0.0043   0.0    8.7	GX 349+2                      
263.0092 -24.7239    4.1   5.3  -78.8   0.2712   2.8    1.3	GX 1+4                        
264.7035 -44.3540   12.4  18.8 -170.3   0.0847   0.9    6.0	4U 1735-44                    
268.2317  -1.4915   10.7  24.3   -0.5  -0.1066  -1.1    8.5	SW J1753.5-0127               
270.2476 -25.1930    5.4   1.5   67.1   0.2235   2.4    7.1	GX 5-1                        
270.3703 -25.6751    7.6   1.5   86.2   0.1902   2.0    5.5	GRS 1758-258                  
273.8464 -13.8923    0.0  12.8   23.6  -0.0528  -0.6   12.7	GX 17+2                       
275.7508 -30.3597    4.9   7.7  128.7   0.2148   2.4    9.0	H1820-303                     
285.1782 -24.7565    0.0  14.9   90.3  -0.1576  -1.5   12.5	HT1900.1-2455                 
288.6402  11.0937    7.5  41.7   30.9   0.3125   1.5   12.9	GRS 1915+105                  
262.9199 -33.9158    5.0   9.5 -148.8   0.2062   2.3    6.0	GX 354-0

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