GRB050827: 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 v2.46
    Process Start Time: Wed Jan 22 20:32:29 EST 2014
             Host Name: batevent1
   Current Working Dir: /local/data/batevent/batevent_reproc/trigger152325
======================================================================

  Trigger: 00152325      Segment: 000

  BAT Trigger Time: 146861834.816   [s; MET]
      Trigger Stop: 146861835.84   [s; MET]
               UTC: 2005-08-27T18:57:15.118740    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 64.2790125123005   Dec: 18.2176224509772  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    8.71
     Image Trigger?:     NO
     Rate S/N Ratio:     24.8596057893121  [ if not an image trigger ]
     Image S/N Ratio:    8.71

  Analysis Position:   [ source = BAT ]
    RA: 64.2790125123005   Dec: 18.2176224509772  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 64.2936814449602   Dec: 18.2179068273975  [deg; J2000]  
        { 04h 17m 10.5s , +18d 13' 04.5" }
         +/- 1.1001741426978 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.339243205319467 [arcmin] (formal 1-sigma fit error)
    SNR: 26.5391959252987
 
  Angular difference between the analysis and refined position is 0.836193 arcmin
 
  Partial Coding Fraction: 0.53125    [ including projection effects ]

  Duration
     T90: 50.0320000052452 +/- 9.12902361374115
        Measured from: -22.7040000259876
                   to: 27.3279999792576     [s; relative to TRIGTIME]
     T50: 10.7520000040531 +/- 1.72429694742584
        Measured from: -6.87200000882149
                   to: 3.87999999523163     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 0.339999973773956     
                   to: 1.33999997377396     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -31.1840000152588     
                   to: 36.1239999830723     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.729243   1.138659   0.946612   0.296056
           0.055561   0.057720   0.048913   0.039434 [error]
 Peak      0.037559   0.090162   0.078089   0.028223
           0.007220   0.008290   0.007587   0.005838 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   67.308  -31.184   36.124
T90    50.032  -22.704   27.328
T50    10.752   -6.872    3.880
Peak    1.000    0.340    1.340
 
 
====== 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      -1.361    -0.098      0.099       -           -               -         3.20e-03     -1.72e-04          1.72e-04      52.650   57
CPL     -1.278    -0.265      0.336      474.100    -474.100      -474.100      3.50e-03     -4.61e-04          1.45e-03      52.680   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      -1.175     -0.169     0.172       -           -               -         1.60e-02     -1.64e-03          1.64e-03      47.950   57
CPL     -0.638     -0.605     0.768      137.550     -52.390      -137.550      2.88e-02     -1.35e-02          3.56e-02      46.010   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   2.41e-07  4.83e-07  7.52e-07  2.58e-06  2.10e-06  4.05e-06   erg/cm2
      90%_error_low -2.53e-08 -3.03e-08 -4.90e-08 -3.61e-07 -1.21e-07 -3.92e-07   erg/cm2
      90%_error_hi   2.62e-08  3.01e-08  4.87e-08  4.01e-07  1.22e-07  4.24e-07   erg/cm2
Peak flux       PL   4.82e-01  5.89e-01  5.22e-01  7.97e-01  1.87e+00  2.39e+00   ph/cm2/s
      90%_error_low -9.09e-02 -7.15e-02 -6.06e-02 -1.77e-01 -1.97e-01 -2.56e-01   ph/cm2/s
      90%_error_hi   9.62e-02  7.06e-02  6.00e-02  2.05e-01  1.97e-01  2.60e-01   ph/cm2/s
 
Fluence        CPL   2.40e-07  4.84e-07  7.55e-07  2.58e-06  2.09e-06  3.93e-06   erg/cm2
      90%_error_low -3.13e-08 -3.14e-08 -5.12e-08 -1.11e-06 -1.29e-07 -9.74e-07   erg/cm2
      90%_error_hi   2.26e-08  3.33e-08  5.52e-08  2.28e-07  1.25e-07  5.23e-07   erg/cm2
Peak flux      CPL   4.29e-01  6.15e-01  5.54e-01  4.66e-01  1.84e+00  2.06e+00   ph/cm2/s
      90%_error_low -1.09e-01 -8.02e-02 -7.25e-02 -2.17e-01 -2.02e-01 -3.03e-01   ph/cm2/s
      90%_error_hi   1.14e-01  8.24e-02  7.44e-02  4.03e-01  2.02e-01  4.53e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   64.2937    18.2179   0.0072    31.1428   145.4037         3.1663713     26.539 TRIG_00152325                 
 
Foreground time interval of the image:
-31.184  36.124 (delta_t =  67.308 [sec])
Background time interval of the image:
-299.816 -31.184 (delta_t = 268.632 [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  -31.184 sec. to   36.124 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.36065     ( -0.0980089   0.0985804 )
Norm@50keV  : 3.19805E-03    ( -0.000172464   0.000172463 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          52.65 using 59 PHA bins.
# Reduced chi-squared =         0.9236 for     57 degrees of freedom 
# Null hypothesis probability =   6.389519e-01
 
Photon flux (15-150 keV)    in 67.31 sec: 0.386133 ( -0.022304  0.022393 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.09768e-06 ( -1.21352e-07  1.21789e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from  -31.184 sec. to   36.124 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.35711     ( -0.240893   0.359816 )
Epeak [keV] : 9995.75      ( -9994.87 -9994.87 )
Norm@50keV  : 3.21038E-03    ( -0.000173131   0.00173813 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          52.64 using 59 PHA bins.
# Reduced chi-squared =         0.9400 for     56 degrees of freedom 
# Null hypothesis probability =   6.027523e-01
 
Photon flux (15-150 keV)    in 67.31 sec: 0.385574 ( -0.02362  0.022635 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.093e-06 ( -1.29329e-07  1.2519e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from    0.340 sec. to    1.340 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.17481     ( -0.168939   0.171902 )
Norm@50keV  : 1.59846E-02    ( -0.00163653   0.00163601 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          47.95 using 59 PHA bins.
# Reduced chi-squared =         0.8412 for     57 degrees of freedom 
# Null hypothesis probability =   7.978453e-01
 
Photon flux (15-150 keV)    in 1 sec: 1.86990 ( -0.19711  0.19744 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.63365e-07 ( -1.82374e-08  1.83329e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    0.340 sec. to    1.340 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.637557     ( -0.605283   0.767922 )
Epeak [keV] : 137.550      ( -52.3901 -137.551 )
Norm@50keV  : 2.87596E-02    ( -0.0135322   0.0356079 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          46.01 using 59 PHA bins.
# Reduced chi-squared =         0.8217 for     56 degrees of freedom 
# Null hypothesis probability =   8.270269e-01
 
Photon flux (15-150 keV)    in 1 sec: 1.83761 ( -0.20167  0.20162 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.58924e-07 ( -1.95024e-08  1.93344e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 50.032 sec.
Hardness ratio (energy fluence ratio) = 1.55765024861

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

S(15-50 keV)  = 7.240372e-07
S(50-150 keV) = 1.3736612e-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 = -4.974078998422721E-01, IMY = -3.430918880556287E-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:
-299.816000 -31.184000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6435  22.0126    0.2  25.0 -176.7  11.8545  67.9    0.6	Crab                          
135.3806 -40.4878    7.7  57.2  -29.7  -2.3963  -1.5    7.9	Vela X-1                      
 84.6755  26.2993    0.7  29.2 -173.3   3.0486  15.6 ------	UNKNOWN                       
 95.6201  55.2180    3.2  58.3 -162.4   3.7868   3.6 ------	UNKNOWN                       
125.1563 -39.0190    2.7  49.8  -25.9   1.9307   4.2 ------	UNKNOWN                       
103.3713  50.5755    2.6  54.9 -155.6   3.0899   4.5 ------	UNKNOWN                       
111.0765  47.1833    2.5  53.9 -148.2   4.1384   4.5 ------	UNKNOWN                       

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

Time interval of the image:
-31.184000 36.124000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.5925  21.8522    4.4  24.9 -176.8  -0.2331  -2.6   10.0	Crab                          
135.4180 -40.4462    8.0  57.2  -29.8   0.6942   1.4    8.2	Vela X-1                      
 49.8025  -4.4394    2.0  37.9   98.5   1.6152   5.7 ------	UNKNOWN                       
 64.2937  18.2179    0.4  31.1  145.4   3.1663  26.5 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
-299.816000 302.260600
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6406  22.0149    0.1  25.0 -176.7  26.4809  83.6    0.4	Crab                          
135.4190 -40.4497    9.8  57.2  -29.8  -4.1400  -1.2    8.0	Vela X-1                      
 64.3128  18.2072    1.6  31.1  145.4   3.5481   7.1 ------	UNKNOWN                       
 84.6951  26.3052    0.5  29.2 -173.3   8.3324  23.3 ------	UNKNOWN                       
 93.8451  10.5380    3.2  14.6 -143.1   1.2887   3.6 ------	UNKNOWN                       
122.6718 -29.9033    2.3  42.8  -34.6   3.0130   4.9 ------	UNKNOWN