batgrbproduct analysis for trigger=290624

batgrbproduct Analysis for Trigger=290624

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 (local time): Mon Jan 20 07:30:42 EST 2014
             Host Name: batevent1
   Current Working Dir: /local/data/batevent/batevent_reproc/trigger290624
======================================================================

  Trigger: 00290624      Segment: 000

  BAT Trigger Time: 211183066.304   [s; MET]
      Trigger Stop: 211183067.328   [s; MET]
               UTC: 2007-09-11T05:57:44.087900    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 25.7991691907814   Dec: -33.4728088428944  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    10.5
     Image Trigger?:     NO
     Rate S/N Ratio:     17.4928556845359  [ if not an image trigger ]
     Image S/N Ratio:    10.5

  Flight Position:   [ source = BAT ]
    RA: 25.7991691907814   Dec: -33.4728088428944  [deg; J2000]

  Ground Position:   [ source = BAT pre-slew burst ]
    RA: 25.8079287869266   Dec: -33.47960099546  [deg; J2000]  
        { 01h 43m 13.9s , -33d 28' 46.6" }
         +/- 0.511717040489844 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.134682943946186 [arcmin] (formal 1-sigma fit error)
    SNR: 79.2118179587907
 
  Angular difference between Flight and Ground position is 0.598554 arcmin
 
  Partial Coding Fraction: 0.8828125    [ including projection effects ]

  Duration
     T90: 161.724000006914 +/- 5.9724691640679
        Measured from: -31.311999976635
                   to: 130.412000030279     [s; relative to TRIGTIME]
     T50: 66.2120000123978 +/- 1.40253058074924
        Measured from: 21.3400000035763
                   to: 87.552000015974     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: 36.1280000209808     
                   to: 37.1280000209808     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -72.2679999768734     
                   to: 158.800000011921     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     6.801907   8.237469   5.395422   1.096555
           0.084948   0.089661   0.078911   0.067938 [error]
 Peak      0.107748   0.182408   0.158121   0.045885
           0.006150   0.007129   0.006862   0.005091 [error]

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

======================================================================
 
=== 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   Power-law 2.13e-06 3.45e-06 4.22e-06 1.02e-05 1.27e-05 2.00e-05   erg/cm2
              Error 8.35e-08 7.53e-08 9.34e-08 5.39e-07 2.29e-07 5.71e-07   erg/cm2
Peak flux Power-law 1.06e+00 1.25e+00 1.07e+00 1.54e+00 3.93e+00 4.92e+00   ph/cm2/s
              Error 8.85e-02 6.33e-02 5.56e-02 1.70e-01 1.76e-01 2.30e-01   ph/cm2/s
 
Fluence   Cutoff-PL 2.10e-06 3.46e-06 4.24e-06 9.46e-06 1.26e-05 1.93e-05   erg/cm2
              Error 1.06e-07 7.96e-08 1.04e-07 1.15e-06 2.62e-07 1.22e-06   erg/cm2
Peak flux Cutoff-PL 9.91e-01 1.28e+00 1.10e+00 1.10e+00 3.87e+00 4.47e+00   ph/cm2/s
              Error 1.08e-01 7.07e-02 6.51e-02 2.75e-01 1.83e-01 3.98e-01   ph/cm2/s
 
Fluence        Band -------- -------- -------- -------- -------- --------   erg/cm2
              Error -------- -------- -------- -------- -------- --------   erg/cm2
Peak flux      Band -------- -------- -------- -------- -------- --------   ph/cm2/s
              Error -------- -------- -------- -------- -------- --------   ph/cm2/s

 
=== Time-averaged spectral analysis ===
 
Model Ph_index Ph_90err Epeak  Epeak_90err Norm     Nomr_90err chi2   dof
PL    1.708    0.037    -      -           5.94e-03 1.06e-04   35.650 57
CPL   1.691    0.098     997.4   -0.0      6.04e-03 5.64e-04   35.610 56
 
 
=== 1-s peak spectral analysis ===
 
Model Ph_index Ph_90err Epeak  Epeak_90err Norm     Nomr_90err chi2   dof
PL    1.231    0.077    -      -           3.33e-02 1.46e-03   53.310 57
CPL   0.920    0.302     186.1  673.9      4.69e-02 1.55e-02   49.970 56
 
Model      : spectral model: simple power-law (PL) and cutoff power-law (CPL)
Ph_index   : photon index: E^-{Ph_index} (minus sign is not included in the 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 PL model and at 1 keV in CPL model
Nomr_90err : 90% error of the normalization
chi2       : Chi-Squared
dof        : degree of freedom

 
=== T90/T50 calculation in the 50-300 keV band (BATSE band) using 64 ms lc ===
 
T90 in the 50-300 keV band: 156.480000 sec.
T50 in the 50-300 keV band: 63.040000 sec.

 
=== Table of the duration information ==
 
        Value   tstart    tstop
T100  231.068  -72.268  158.800
T90   161.724  -31.312  130.412
T50    66.212   21.340   87.552
Peak    1.000   36.128   37.128

Click here for the BAT GCN circular template

Image

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

#   RAcent    DECcent   POSerr    Theta     Phi              Peak Cts       SNR   Name
   25.8079   -33.4796   0.0024    21.2473   156.5654        14.4271489     79.212 TRIG_00290624                 
 
Foreground time interval of the image:
-72.268  74.797 (delta_t = 147.065 [sec])
Background time interval of the image:
-299.304 -72.268 (delta_t = 227.036 [sec])

Lightcurves

Notes:

1) The mask-weighted light curves are using the flight position.
2) Multiple plots of different time binning/intervals are shown to cover all scenarios of short/long GRBs, rate/image triggers, and real/false positives.
3) For all the mask-weighted lightcurves, the y-axis units are counts/sec/det where a det is 0.4 x 0.4 = 0.16 sq cm.
4) The verticle lines correspond to following: green dotted lines are T50 interval, black dotted lines are T90 interval, blue solid line(s) is a spacecraft slew start time, and orange solid line(s) is a spacecraft slew end time.
5) Time of each bin is in the middle of the bin.

1 s binning

From T0-310 s to T0+310 s

From T100_start - 20 s to T100_end + 30 s

Full time interval

64 ms binning

Full time interval

From T100_start to T100_end

From T0-5 sec to T0+5 sec

16 ms binning

From T100_start-5 s to T100_start+5 s

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

8 ms binning

From T100_start-3 s to T100_start+3 s

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

2 ms binning

From T100_start-1 s to T100_start+1 s

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

SN=5 or 10 sec. binning (whichever binning is satisfied first)

SN=5 or 10 sec. binning (T < 200 sec)

Quad-rate summed light curves (from T0-300s to T0+1000s)

Spectral Evolution

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  -72.268 sec. to  158.800 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.70796     ( -0.0368563   0.0368769 )
Norm@50keV  : 5.93524E-03    ( -0.00010611   0.00010611 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          35.65 using 59 PHA bins.
# Reduced chi-squared =         0.6255 for     57 degrees of freedom 
# Null hypothesis probability =   9.880496e-01
 
Photon flux (15-150 keV)    in 231.1 sec: 0.790471 ( -0.0174981  0.0175958 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.26919e-05 ( -2.29268e-07  2.2936e-07 ) ergs/cm2

Cutoff power-law model

Time interval is from  -72.268 sec. to  158.800 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.69065     ( -0.144583   0.0507616 )
Epeak [keV] : 997.361      ( -999.113 -999.123 )
Norm@50keV  : 6.04176E-03    ( -0.000192691   0.000935889 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          35.61 using 59 PHA bins.
# Reduced chi-squared =         0.6359 for     56 degrees of freedom 
# Null hypothesis probability =   9.846971e-01
 
Photon flux (15-150 keV)    in 231.1 sec: 0.785257 ( -0.009152  0.022773 ) ph/cm2/s
Energy fluence (15-150 keV)             : 1.26421e-05 ( -2.39281e-07  2.85432e-07 ) ergs/cm2

Band function

Time interval is from  -72.268 sec. to  158.800 sec.
 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       : 2.13290   ( -2.19052   -2.19052 )
beta        : -1.72008    ( -0.0384433   0.0382057 )
Epeak [keV] : 24.2900      ( -24.3903 120.738 )
Norm@50keV   : 5.93551    ( -0.44338   550.121 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          33.74 using 59 PHA bins.
# Reduced chi-squared =         0.6135 for     55 degrees of freedom 
# Null hypothesis probability =   9.893764e-01
 
Photon flux (15-150 keV)    in 231.1 sec:  (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 0 ( 0  0 ) ergs/cm2

Single BB

 
Spectral model blackbody:
------------------------------------------------------------
Parameters  : value    Lower 90%  Upper 90%
kT [keV]    : 15.8390  (  )
R^2/D10^2   : 6.45536E-02  (   )
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared =         736.58 using 59 PHA bins.
# Reduced chi-squared =         12.923 for     57 degrees of freedom 
# Null hypothesis probability =  7.907112e-119
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  7.755e-07   3.062e-08
25- 50  3.235e-06   8.204e-08
50-150  5.651e-06   1.779e-07
15-150  9.662e-06   1.964e-07

Thermal bremsstrahlung (OTTB)

 
 
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT [keV]    : 156.569       (      )
Norm        : 3.14182       (-0.0825406     0.0811774)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          56.17 using 59 PHA bins.
# Reduced chi-squared =         0.9854 for     57 degrees of freedom 
# Null hypothesis probability =   5.063211e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  1.842e-06   8.620e-08
25- 50  3.439e-06   1.502e-07
50-150  6.932e-06   1.420e-06
15-150  1.221e-05   1.485e-06

Double BB

 
 
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT1 [keV]   : 7.34084        (-0.476585      0.502112)
R1^2/D10^2  : 0.752726        (-0.160666      0.216051)
kT2 [keV]   : 27.9078        (-1.89541      2.2908)
R2^2/D10^2  : 6.69252E-03    (-0.00165594   0.00198602)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          51.93 using 59 PHA bins.
# Reduced chi-squared =         0.9442 for     55 degrees of freedom 
# Null hypothesis probability =   5.925732e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  1.775e-06   1.175e-07
25- 50  3.542e-06   1.156e-07
50-150  7.101e-06   3.039e-07
15-150  1.242e-05   3.721e-07

Peak spectrum fit

Power-law model

Time interval is from   36.128 sec. to   37.128 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.23136     ( -0.0770091   0.0768848 )
Norm@50keV  : 3.33099E-02    ( -0.00146311   0.00146292 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          53.31 using 59 PHA bins.
# Reduced chi-squared =         0.9352 for     57 degrees of freedom 
# Null hypothesis probability =   6.143438e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.92803 ( -0.176357  0.176479 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.35026e-07 ( -1.65619e-08  1.6624e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from   36.128 sec. to   37.128 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 0.920093     ( -0.313275   0.291372 )
Epeak [keV] : 186.054      ( -67.577 1280.31 )
Norm@50keV  : 4.68848E-02    ( -0.012407   0.0186132 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          49.97 using 59 PHA bins.
# Reduced chi-squared =         0.8923 for     56 degrees of freedom 
# Null hypothesis probability =   7.012455e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.87486 ( -0.18303  0.18299 ) ph/cm2/s
Energy fluence (15-150 keV)             : 3.28548e-07 ( -1.7979e-08  1.7868e-08 ) ergs/cm2

Band function

Time interval is from   36.128 sec. to   37.128 sec.
 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       : 2.04138   ( -2.83168   -2.04137 )
beta        : -1.33201    ( -0.11743   0.106318 )
Epeak [keV] : 34.9115      ( -6.5035 98.2421 )
Norm@50keV   : 6.19896    ( -6.19873   450.47 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          46.61 using 59 PHA bins.
# Reduced chi-squared =         0.8475 for     55 degrees of freedom 
# Null hypothesis probability =   7.822904e-01
 
Photon flux (15-150 keV)    in 1 sec:  (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 0 ( 0  0 ) ergs/cm2

Single BB

 
Spectral model blackbody:
------------------------------------------------------------
Parameters  : value    Lower 90%  Upper 90%
kT [keV]    : 18.0050  (  )
R^2/D10^2   : 0.252870  (   )
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared =         145.31 using 59 PHA bins.
# Reduced chi-squared =         2.5493 for     57 degrees of freedom 
# Null hypothesis probability =   1.184280e-09
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  1.641e-08   1.380e-09
25- 50  7.592e-08   4.465e-09
50-150  1.787e-07   1.520e-08
15-150  2.710e-07   1.470e-08

Thermal bremsstrahlung (OTTB)

 
 
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT [keV]    : 200.000       (      )
Norm        : 16.1831       (-0.72131     0.721221)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          96.72 using 59 PHA bins.
# Reduced chi-squared =          1.697 for     57 degrees of freedom 
# Null hypothesis probability =   8.035078e-04
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  4.031e-08   1.930e-09
25- 50  7.753e-08   3.625e-09
50-150  1.700e-07   8.350e-09
15-150  2.879e-07   1.390e-08

Double BB

 
 
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT1 [keV]   : 8.53035        (-1.28335      1.44089)
R1^2/D10^2  : 1.81131        (-0.658036      1.16862)
kT2 [keV]   : 33.1990        (-5.32108      9.00178)
R2^2/D10^2  : 2.72622E-02    (-0.0145026   0.0220771)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          46.27 using 59 PHA bins.
# Reduced chi-squared =         0.8412 for     55 degrees of freedom 
# Null hypothesis probability =   7.929408e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  2.930e-08   4.860e-09
25- 50  7.684e-08   1.006e-08
50-150  2.258e-07   5.140e-08
15-150  3.320e-07   6.160e-08

Pre-slew spectrum (Pre-slew PHA with pre-slew DRM)

Power-law model

 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.60899     ( -0.0367234   0.036723 )
Norm@50keV  : 6.44766E-03    ( -0.000117151   0.000117143 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          33.27 using 59 PHA bins.
# Reduced chi-squared =         0.5837 for     57 degrees of freedom 
# Null hypothesis probability =   9.949546e-01
 
Photon flux (15-150 keV)    in 147.1 sec: 0.830872 ( -0.0181779  0.0182733 ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.86049e-06 ( -1.63766e-07  1.63871e-07 ) ergs/cm2

Cutoff power-law model

Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.55268     ( -0.147781   0.0725033 )
Epeak [keV] : 447.589      ( -447.59 -447.59 )
Norm@50keV  : 6.82822E-03    ( -0.000465496   0.00107748 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          32.83 using 59 PHA bins.
# Reduced chi-squared =         0.5863 for     56 degrees of freedom 
# Null hypothesis probability =   9.942855e-01
 
Photon flux (15-150 keV)    in 147.1 sec: 0.826186 ( -0.021359  0.02103 ) ph/cm2/s
Energy fluence (15-150 keV)             : 8.82821e-06 ( -1.88303e-07  1.85449e-07 ) ergs/cm2

Band function

 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       : -7.42483E-02   ( -2.35698   0.0733498 )
beta        : -1.62782    ( -0.0466103   0.0424797 )
Epeak [keV] : 34.2013      ( -10.9332 65.4033 )
Norm@50keV   : 7.71915E-02    ( -0.0776651   422.825 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          30.40 using 59 PHA bins.
# Reduced chi-squared =         0.5528 for     55 degrees of freedom 
# Null hypothesis probability =   9.971381e-01
 
Photon flux (15-150 keV)    in 147.1 sec:  (    ) ph/cm2/s
Energy fluence (15-150 keV)             : 0 ( 0  0 ) ergs/cm2

S(25-50 keV) vs. S(50-100 keV) plot

S(25-50 keV)  = 3.45e-06
S(50-100 keV) = 4.22e-06

T90 vs. Hardness ratio plot

T90                                   = 161.724000006914 sec.
Hardness ratio (energy fluence ratio) = 1.22319

Color vs. Color plot

Count Ratio  (25-50 keV) / (15-25 keV) = 1.21105
Count Ratio (50-100 keV) / (15-25 keV) = 0.793222

Mask shadow pattern

IMX = -3.567525846678423E-01, IMY = -1.546368169387835E-01

TIME vs. PHA plot around the trigger time

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

TIME vs. DetID plot around the trigger time

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

100 us light curve (15-350 keV)

Blue+Cyan dotted lines: Time interval of the scaled map
From 0.000000 to 1.024000

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:
-299.304000 -72.268000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
243.4304 -72.6155    3.1  50.7  -44.5   3.1459   3.8 ------	UNKNOWN                       
 91.5938 -67.3851    4.0  41.0  -98.1   2.3104   2.9 ------	UNKNOWN                       
 84.5598 -43.9766    3.3  48.7 -130.2   2.5682   3.6 ------	UNKNOWN

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

Time interval of the image:
-72.268000 74.796590
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
328.7869 -27.7587    2.2  38.7   48.9   2.0922   5.2 ------	UNKNOWN                       
295.0636 -34.3386    2.6  54.9   14.4   4.2761   4.4 ------	UNKNOWN                       
 25.8079 -33.4796    0.1  21.2  156.6  14.4098  79.1 ------	UNKNOWN                       
 43.3539 -62.6310    2.4  21.1 -107.4   0.9262   4.8 ------	UNKNOWN                       
254.6895 -63.8640    3.6  54.3  -33.3   2.8475   3.2 ------	UNKNOWN                       
 85.6606 -49.4397    2.5  46.2 -123.6   3.5307   4.6 ------	UNKNOWN

Post-slew image of 15-350 keV band

Time interval of the image:
125.996590 302.776000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
 25.8048 -33.4748    1.1  29.6  107.1   2.3601  10.8 ------	UNKNOWN                       
 61.8269 -41.6068    2.5  14.2 -176.3   0.5486   4.6 ------	UNKNOWN                       
105.9006 -27.0453    3.0  46.1 -123.8   2.3606   3.9 ------	UNKNOWN

Plot creation:
Sun May 31 09:21:11 EDT 2015