GRB050418: 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 22:18:41 EST 2014
             Host Name: batevent1
   Current Working Dir: /local/data/batevent/batevent_reproc/trigger114893
======================================================================

  Trigger: 00114893      Segment: 000

  BAT Trigger Time: 135514834.112   [s; MET]
      Trigger Stop: 135514835.136   [s; MET]
               UTC: 2005-04-18T11:00:34.629320    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 44.3414527693041   Dec: -18.5378750599418  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    18
     Image Trigger?:     NO
     Rate S/N Ratio:     39.6358423652128  [ if not an image trigger ]
     Image S/N Ratio:    18

  Analysis Position:   [ source = BAT ]
    RA: 44.3414527693041   Dec: -18.5378750599418  [deg; J2000]

  Refined Position:   [ source = BAT pre-slew burst ]
    RA: 44.3380615840616   Dec: -18.5417626500121  [deg; J2000]  
        { 02h 57m 21.1s , -18d 32' 30.3" }
         +/- 0.781390523424029 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.235490138407183 [arcmin] (formal 1-sigma fit error)
    SNR: 43.2677084313888
 
  Angular difference between the analysis and refined position is 0.302693 arcmin
 
  Partial Coding Fraction: 0.359375    [ including projection effects ]

  Duration
     T90: 81.7599999904633 +/- 1.37141680359854
        Measured from: -5.09199997782707
                   to: 76.6680000126362     [s; relative to TRIGTIME]
     T50: 61.444000005722 +/- 2.0065582513695
        Measured from: 1.03600001335144
                   to: 62.4800000190735     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 0.724000006914139     
                   to: 1.72400000691414     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -8.35199999809265     
                   to: 80.5600000023842     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     2.252066   3.118329   2.210254   0.475391
           0.079319   0.083062   0.072214   0.058159 [error]
 Peak      0.073687   0.149349   0.178855   0.037019
           0.009581   0.010911   0.010918   0.007733 [error]

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

======================================================================
 
 
====== Table of the duration information =============================
 
        Value   tstart    tstop
T100   88.912   -8.352   80.560
T90    81.760   -5.092   76.668
T50    61.444    1.036   62.480
Peak    1.000    0.724    1.724
 
 
====== 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: 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      -1.665    -0.060      0.060       -           -               -         6.34e-03     -2.10e-04          2.10e-04      56.950   57
CPL     -1.280    -0.246      0.261       98.153     -20.246        76.991      9.69e-03     -2.25e-03          3.15e-03      49.640   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      -1.106     -0.118     0.120       -           -               -         3.20e-02     -2.32e-03          2.32e-03      59.390   57
CPL     -0.402     -0.520     0.592      130.668     -34.949       188.900      6.61e-02     -2.69e-02          5.19e-02      53.860   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   8.40e-07  1.40e-06  1.76e-06  4.43e-06  5.23e-06  8.43e-06   erg/cm2
      90%_error_low -5.07e-08 -5.03e-08 -7.43e-08 -3.99e-07 -1.80e-07 -4.50e-07   erg/cm2
      90%_error_hi   5.18e-08  5.01e-08  7.41e-08  4.24e-07  1.80e-07  4.69e-07   erg/cm2
Peak flux       PL   9.04e-01  1.15e+00  1.07e+00  1.74e+00  3.71e+00  4.87e+00   ph/cm2/s
      90%_error_low -1.26e-01 -1.03e-01 -8.35e-02 -2.68e-01 -2.79e-01 -3.66e-01   ph/cm2/s
      90%_error_hi   1.32e-01  1.02e-01  8.30e-02  2.96e-01  2.80e-01  3.69e-01   ph/cm2/s
 
Fluence        CPL   7.74e-07  1.44e-06  1.81e-06  2.67e-06  5.10e-06  6.70e-06   erg/cm2
      90%_error_low -6.38e-08 -5.70e-08 -8.21e-08 -6.91e-07 -2.00e-07 -7.15e-07   erg/cm2
      90%_error_hi   6.50e-08  5.76e-08  8.28e-08  9.89e-07  1.99e-07  9.95e-07   erg/cm2
Peak flux      CPL   7.54e-01  1.20e+00  1.17e+00  9.56e-01  3.63e+00  4.08e+00   ph/cm2/s
      90%_error_low -1.60e-01 -1.14e-01 -1.10e-01 -3.17e-01 -2.87e-01 -4.39e-01   ph/cm2/s
      90%_error_hi   1.67e-01  1.15e-01  1.12e-01  5.22e-01  2.87e-01  5.74e-01   ph/cm2/s
 
======================================================================

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   44.3381   -18.5418   0.0045    39.4241  -133.7721         8.0678544     43.268 TRIG_00114893                 
 
Foreground time interval of the image:
 -8.352  80.560 (delta_t =  88.912 [sec])
Background time interval of the image:
-177.811  -8.352 (delta_t = 169.459 [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   -8.352 sec. to   80.560 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.6651     ( -0.0601248   0.0599501 )
Norm@50keV  : 6.33833E-03    ( -0.000209769   0.000209644 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          56.95 using 59 PHA bins.
# Reduced chi-squared =         0.9992 for     57 degrees of freedom 
# Null hypothesis probability =   4.768298e-01
 
Photon flux (15-150 keV)    in 88.91 sec: 0.831824 ( -0.029922  0.030018 ) ph/cm2/s
Energy fluence (15-150 keV)             : 5.2342e-06 ( -1.79791e-07  1.80201e-07 ) ergs/cm2
 

Cutoff power-law model

Time interval is from   -8.352 sec. to   80.560 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.28024     ( -0.246239   0.260749 )
Epeak [keV] : 98.1535      ( -20.2459 76.9903 )
Norm@50keV  : 9.69176E-03    ( -0.00225437   0.00314618 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          49.64 using 59 PHA bins.
# Reduced chi-squared =         0.8864 for     56 degrees of freedom 
# Null hypothesis probability =   7.128029e-01
 
Photon flux (15-150 keV)    in 88.91 sec: 0.810446 ( -0.032537  0.032719 ) ph/cm2/s
Energy fluence (15-150 keV)             : 5.10153e-06 ( -1.99788e-07  1.99014e-07 ) ergs/cm2
 

1-s peak spectrum fit

Power-law model

Time interval is from    0.724 sec. to    1.724 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -1.10619     ( -0.118147   0.119893 )
Norm@50keV  : 3.20035E-02    ( -0.00232446   0.00232114 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          59.39 using 59 PHA bins.
# Reduced chi-squared =          1.042 for     57 degrees of freedom 
# Null hypothesis probability =   3.885153e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.71444 ( -0.27904  0.27957 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.3398e-07 ( -2.55689e-08  2.56617e-08 ) ergs/cm2
 

Cutoff power-law model

Time interval is from    0.724 sec. to    1.724 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: -0.401569     ( -0.52004   0.592323 )
Epeak [keV] : 130.668      ( -34.9486 188.9 )
Norm@50keV  : 6.60825E-02    ( -0.0268736   0.0518611 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          53.86 using 59 PHA bins.
# Reduced chi-squared =         0.9618 for     56 degrees of freedom 
# Null hypothesis probability =   5.561914e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.62933 ( -0.28659  0.28686 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.26392e-07 ( -2.68415e-08  2.67261e-08 ) ergs/cm2
 

Time-resolved spectra

Distribution

T90 vs. Hardness ratio plot

T90                                   = 81.76 sec.
Hardness ratio (energy fluence ratio) = 1.25994010638

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

S(15-50 keV)  = 2.2113439e-06
S(50-150 keV) = 2.890202e-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 = -5.687324730072576E-01, IMY = 5.936468677865748E-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:
-177.811430 -8.352000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6359  22.0191    0.2  27.5  -18.8   7.0834  53.7    0.3	Crab                          
122.9389  -5.5670    3.0  40.2   71.0   1.9078   3.9 ------	UNKNOWN                       
 95.7994 -28.4715    2.3  26.2  131.7   0.8132   5.0 ------	UNKNOWN                       
 50.3733 -56.4354    2.7  56.9  179.5   2.9289   4.3 ------	UNKNOWN                       
 88.7405  19.2148    2.6  25.5   -7.3   0.5582   4.4 ------	UNKNOWN                       
 45.8930  13.3891    2.6  41.0  -83.3   2.5366   4.4 ------	UNKNOWN                       
 42.4754   4.2922    3.7  41.2  -98.1   2.2049   3.1 ------	UNKNOWN                       

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

Time interval of the image:
-8.352000 80.560000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.4569  21.9145  846.2  27.4  -19.2   0.0015   0.0   11.5	Crab                          
 99.8975 -10.4741    2.9  17.9   86.1   0.4823   4.0 ------	UNKNOWN                       
 75.5733 -44.1616    2.2  39.1  166.8   0.8775   5.2 ------	UNKNOWN                       
 75.9463  -3.2078    2.4   6.9  -92.0   0.4888   4.8 ------	UNKNOWN                       
 44.3381 -18.5418    0.3  39.4 -133.8   8.0671  43.3 ------	UNKNOWN                       

Post-slew image of 15-350 keV band

Time interval of the image:
-299.112000 302.936500
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 83.6329  22.0188    0.2  27.5  -18.8  20.2288  64.9    0.3	Crab                          
125.0067  10.2696    3.5  45.2   48.5   4.3538   3.3 ------	UNKNOWN                       
 84.4364 -21.6516    3.2  16.3  152.5   1.1403   3.6 ------	UNKNOWN                       
 34.7288 -48.5267    3.0  59.0 -166.2   9.7247   3.9 ------	UNKNOWN                       
 44.3339 -18.5398    0.9  39.4 -133.8   8.1115  13.2 ------	UNKNOWN