batgrbproduct analysis for trigger=850231

batgrbproduct Analysis for Trigger=850231

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): Fri Oct 26 17:11:16 EDT 2018
             Host Name: bat1
   Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/trigger850231
======================================================================

  Trigger: 00850231      Segment: 000

  BAT Trigger Time: 554393750.016   [s; MET]
      Trigger Stop: 554393751.04   [s; MET]
               UTC: 2018-07-27T14:15:28.684460    [includes UTCF correction] 
       Where From?: TDRSS position message

  BAT 
    RA: 346.638589844321   Dec: -63.0635521810573  [deg; J2000]

     Catalogged Source?: NO
     Point Source?:      YES
     GRB Indicated?:     YES    [ by BAT flight software ]
     Image S/N Ratio:    18.03
     Image Trigger?:     NO
     Rate S/N Ratio:     49.2138191974571  [ if not an image trigger ]
     Image S/N Ratio:    18.03

  Flight Position:   [ source = BAT ]
    RA: 346.638589844321   Dec: -63.0635521810573  [deg; J2000]

  Ground Position:   [ source = BAT pre-slew burst ]
    RA: 346.638682341704   Dec: -63.066072614268  [deg; J2000]  
        { 23h 06m 33.3s , -63d 03' 57.9" }
         +/- 1.11315718085439 [arcmin] (estimated 90% radius based on SNR)
         +/- 0.378013336151439 [arcmin] (formal 1-sigma fit error)
    SNR: 26.0981128886752
 
  Angular difference between Flight and Ground position is 0.151247 arcmin
 
  Partial Coding Fraction: 0.859375    [ including projection effects ]

  Duration
     T90: 1.05599999427795 +/- 0.229120086267606
        Measured from: 0.0239999294281006
                   to: 1.07999992370605     [s; relative to TRIGTIME]
     T50: 0.452000021934509 +/- 0.0707672428107233
        Measured from: 0.25599992275238
                   to: 0.70799994468689     [s; relative to TRIGTIME]



  Fluence
     Peak Flux  (peak 1 second)
        Measured from: -0.0520000457763672     
                   to: 0.947999954223633     [s; relative to TRIGTIME]
     Total Fluence        
        Measured from: -0.0520000457763672     
                   to: 1.33200001716614     [s; relative to TRIGTIME]
     
             Band 1     Band 2     Band 3     Band 4
              15-25      25-50     50-100    100-350     keV
 Total     0.148990   0.193082   0.134374   0.018533
           0.009851   0.010739   0.009288   0.006924 [error]
 Peak      0.129810   0.175371   0.126329   0.017944
           0.008712   0.009849   0.008540   0.006074 [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 4.40e-08 7.61e-08 1.01e-07 2.71e-07 2.93e-07 4.91e-07   erg/cm2
              Error 4.37e-09 4.87e-09 8.73e-09 4.82e-08 2.11e-08 5.60e-08   erg/cm2
Peak flux Power-law 1.23e+00 1.21e+00 8.29e-01 8.98e-01 3.62e+00 4.16e+00   ph/cm2/s
              Error 1.24e-01 7.89e-02 6.78e-02 1.43e-01 2.30e-01 2.67e-01   ph/cm2/s
 
Fluence   Cutoff-PL 3.78e-08 8.48e-08 1.05e-07 7.65e-08 2.74e-07 3.04e-07   erg/cm2
              Error 5.25e-09 6.44e-09 1.01e-08 4.29e-08 2.27e-08 4.74e-08   erg/cm2
Peak flux Cutoff-PL 1.02e+00 1.34e+00 9.00e-01 3.21e-01 3.50e+00 3.59e+00   ph/cm2/s
              Error 1.49e-01 1.01e-01 8.08e-02 1.40e-01 2.37e-01 2.72e-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    1.599    0.106    -      -           2.27e-02 1.51e-03   57.460 57
CPL   0.588    0.515      67.6   14.8      7.58e-02 5.01e-02   43.230 56
 
 
=== 1-s peak spectral analysis ===
 
Model Ph_index Ph_90err Epeak  Epeak_90err Norm     Nomr_90err chi2   dof
PL    1.540    0.102    -      -           2.87e-02 1.88e-03   69.570 57
CPL   0.449    0.511      69.7   14.0      1.05e-01 6.78e-02   52.330 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: 0.832000 sec.
T50 in the 50-300 keV band: 0.384000 sec.

 
=== Table of the duration information ==
 
        Value   tstart    tstop
T100    1.384   -0.052    1.332
T90     1.056    0.024    1.080
T50     0.452    0.256    0.708
Peak    1.000   -0.052    0.948

Click here for the BAT GCN circular template

Estimated redshift from machine learning (Ukwatta et al. 2016) - may take a few minute to calcaulte

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
  346.6387   -63.0661   0.0074    16.9953    53.7999         0.5245691     26.098 TRIG_00850231                 
 
Foreground time interval of the image:
 -0.052   1.332 (delta_t =   1.384 [sec])
Background time interval of the image:
-239.016  -0.052 (delta_t = 238.964 [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   -0.052 sec. to    1.332 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.59876     ( -0.104776   0.106402 )
Norm@50keV  : 2.27103E-02    ( -0.00151234   0.00150414 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          57.46 using 59 PHA bins.
# Reduced chi-squared =          1.008 for     57 degrees of freedom 
# Null hypothesis probability =   4.580432e-01
 
Photon flux (15-150 keV)    in 1.384 sec: 2.91736 ( -0.18526  0.18537 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.94034e-07 ( -2.09874e-08  2.11446e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from   -0.052 sec. to    1.332 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 0.588052     ( -0.545776   0.484203 )
Epeak [keV] : 67.6269      ( -9.58309 20.0558 )
Norm@50keV  : 7.57856E-02    ( -0.0326754   0.0674652 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          43.23 using 59 PHA bins.
# Reduced chi-squared =         0.7720 for     56 degrees of freedom 
# Null hypothesis probability =   8.940943e-01
 
Photon flux (15-150 keV)    in 1.384 sec: 2.80723 ( -0.19251  0.19236 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.74377e-07 ( -2.253e-08  2.28968e-08 ) ergs/cm2

Band function

Time interval is from   -0.052 sec. to    1.332 sec.
 
 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       :    (     )
beta        :     (     )
Epeak [keV] :       (   )
Norm@50keV   :     (     )
------------------------------------------------------------
 
Photon flux (15-150 keV)    in  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]    : 13.9844  (-0.958851  1.03298)
R^2/D10^2   : 0.432203  (-0.0975403   0.124789)
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          71.16 using 59 PHA bins.
# Reduced chi-squared =          1.248 for     57 degrees of freedom 
# Null hypothesis probability =   9.827517e-02
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  2.471e-08   2.927e-09
25- 50  9.181e-08   7.280e-09
50-150  1.182e-07   1.620e-08
15-150  2.347e-07   1.917e-08

Thermal bremsstrahlung (OTTB)

 
 
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT [keV]    : 158.672       (-39.0815      -158.868)
Norm        : 12.1290       (-0.842095     0.899479)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          48.88 using 59 PHA bins.
# Reduced chi-squared =         0.8576 for     57 degrees of freedom 
# Null hypothesis probability =   7.692299e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  4.290e-08   3.522e-09
25- 50  8.015e-08   1.262e-08
50-150  1.618e-07   6.202e-08
15-150  2.849e-07   6.989e-08

Double BB

 
 
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT1 [keV]   : 4.82493        (-1.38644      2.4656)
R1^2/D10^2  : 8.51027        (-6.41697      28.9402)
kT2 [keV]   : 17.3506        (-1.95278      3.62683)
R2^2/D10^2  : 0.174571    (-0.0984789   0.0876741)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          43.24 using 59 PHA bins.
# Reduced chi-squared =         0.7861 for     55 degrees of freedom 
# Null hypothesis probability =   8.746339e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  3.951e-08   1.591e-08
25- 50  8.103e-08   1.841e-08
50-150  1.437e-07   2.686e-08
15-150  2.643e-07   4.588e-08

Peak spectrum fit

Power-law model

Time interval is from   -0.052 sec. to    0.948 sec.
 
Spectral model in power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 1.54038     ( -0.101711   0.103043 )
Norm@50keV  : 2.86945E-02    ( -0.00188634   0.00187848 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          69.57 using 59 PHA bins.
# Reduced chi-squared =          1.220 for     57 degrees of freedom 
# Null hypothesis probability =   1.227152e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.62263 ( -0.23014  0.23025 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.70545e-07 ( -1.92407e-08  1.93695e-08 ) ergs/cm2

Cutoff power-law model

Time interval is from   -0.052 sec. to    0.948 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 0.449360     ( -0.541507   0.479801 )
Epeak [keV] : 69.6771      ( -9.46611 18.4737 )
Norm@50keV  : 0.104544    ( -0.0445468   0.0910979 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          52.33 using 59 PHA bins.
# Reduced chi-squared =         0.9344 for     56 degrees of freedom 
# Null hypothesis probability =   6.146787e-01
 
Photon flux (15-150 keV)    in 1 sec: 3.49799 ( -0.23704  0.23674 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.53087e-07 ( -2.04654e-08  2.07297e-08 ) ergs/cm2

Band function

Time interval is from   -0.052 sec. to    0.948 sec.
 
 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       :    (     )
beta        :     (     )
Epeak [keV] :       (   )
Norm@50keV   :     (     )
------------------------------------------------------------
 
Photon flux (15-150 keV)    in  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]    : 14.4569  (-0.973068  1.04748)
R^2/D10^2   : 0.489903  (-0.108146   0.137158)
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          77.49 using 59 PHA bins.
# Reduced chi-squared =          1.359 for     57 degrees of freedom 
# Null hypothesis probability =   3.683538e-02
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  2.155e-08   2.440e-09
25- 50  8.271e-08   6.725e-09
50-150  1.157e-07   1.409e-08
15-150  2.199e-07   1.690e-08

Thermal bremsstrahlung (OTTB)

 
 
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT [keV]    : 188.446       (-51.5239      -190.109)
Norm        : 14.9433       (-0.960912     1.01694)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          60.72 using 59 PHA bins.
# Reduced chi-squared =          1.065 for     57 degrees of freedom 
# Null hypothesis probability =   3.432992e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  3.748e-08   3.485e-09
25- 50  7.161e-08   2.025e-08
50-150  1.541e-07   6.825e-08
15-150  2.632e-07   8.350e-08

Double BB

 
 
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters  : value         Lower 90%    Upper 90%
kT1 [keV]   : 5.05757        (-1.53525      3.27708)
R1^2/D10^2  : 8.03717        (-6.30952      28.8357)
kT2 [keV]   : 17.7664        (-2.01784      4.86941)
R2^2/D10^2  : 0.206171    (-0.136689   0.105412)
------------------------------------------------------------
#Fit statistic : Chi-Squared =          52.94 using 59 PHA bins.
# Reduced chi-squared =         0.9625 for     55 degrees of freedom 
# Null hypothesis probability =   5.538890e-01
 
Energy  Fluence     90% Error
[keV]   [erg/cm2]   [erg/cm2]
15- 25  3.354e-08   1.284e-08
25- 50  7.366e-08   1.469e-08
50-150  1.374e-07   2.641e-08
15-150  2.446e-07   4.440e-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: 1.59876     ( -0.104776   0.106402 )
Norm@50keV  : 2.27103E-02    ( -0.00151234   0.00150414 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          57.46 using 59 PHA bins.
# Reduced chi-squared =          1.008 for     57 degrees of freedom 
# Null hypothesis probability =   4.580432e-01
 
Photon flux (15-150 keV)    in 1.384 sec: 2.91726 ( -0.185247  0.185356 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.93993e-07 ( -2.10039e-08  2.11478e-08 ) ergs/cm2

Cutoff power-law model

Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
Photon index: 0.588052     ( -0.545776   0.484203 )
Epeak [keV] : 67.6269      ( -9.58309 20.0558 )
Norm@50keV  : 7.57856E-02    ( -0.0326753   0.0674652 )
------------------------------------------------------------
#Fit statistic : Chi-Squared =          43.23 using 59 PHA bins.
# Reduced chi-squared =         0.7720 for     56 degrees of freedom 
# Null hypothesis probability =   8.940943e-01
 
Photon flux (15-150 keV)    in 1.384 sec: 2.80694 ( -0.19247  0.1923 ) ph/cm2/s
Energy fluence (15-150 keV)             : 2.74473e-07 ( -2.25578e-08  2.2908e-08 ) ergs/cm2

Band function

 
 
Spectral model in the Band function:
------------------------------------------------------------
Parameters  : value       lower 90%   higher 90%
alpha       :    (     )
beta        :     (     )
Epeak [keV] :       (   )
Norm@50keV   :     (     )
------------------------------------------------------------
 
Photon flux (15-150 keV)    in  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)  = 7.61e-08
S(50-100 keV) = 1.01e-07

T90 vs. Hardness ratio plot

T90                                   = 1.05599999427795 sec.
Hardness ratio (energy fluence ratio) = 1.3272

Color vs. Color plot

Count Ratio  (25-50 keV) / (15-25 keV) = 1.29594
Count Ratio (50-100 keV) / (15-25 keV) = 0.901899

Mask shadow pattern

IMX = 1.805139349500686E-01, IMY = -2.466397747629926E-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:
-239.016000 -0.052000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
170.0935 -60.5779   25.5  58.2  -24.4   0.6764   0.5    7.1	Cen X-3                       
186.8030 -62.7862    4.4  57.9  -14.8   3.0083   2.6    4.1	GX 301-2                      
303.6396 -58.1132    2.5  38.2   49.4   2.2344   4.6 ------	UNKNOWN                       
 56.0102 -39.8771    3.0  29.1 -122.2   1.2008   3.9 ------	UNKNOWN                       
 68.9322 -48.9315    3.2  29.2  -95.5   1.2710   3.6 ------	UNKNOWN                       
 60.5981 -16.9365    2.7  50.9 -135.4   6.1991   4.3 ------	UNKNOWN

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

Time interval of the image:
-0.052000 1.332000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
170.5887 -60.5932    3.9  58.3  -24.2  -0.3032  -3.0    8.2	Cen X-3                       
186.4959 -62.7253    4.7  58.0  -14.9   0.2104   2.4    5.2	GX 301-2                      
331.1148 -36.1819    2.3  39.2   95.5   0.3598   5.1 ------	UNKNOWN                       
  7.6073  -9.3519    2.0  50.5  155.6   0.4032   5.7 ------	UNKNOWN                       
346.6387 -63.0661    0.4  17.0   53.8   0.5246  26.1 ------	UNKNOWN                       
 55.0236 -36.3595    2.1  31.5 -127.5   0.1300   5.6 ------	UNKNOWN                       
114.3485 -56.5370    2.3  45.8  -57.3   0.3397   5.0 ------	UNKNOWN

Post-slew image of 15-350 keV band

Time interval of the image:
55.684610 363.104000
 
# RAcent  DECcent POSerr Theta    Phi  PeakCts   SNR AngSep     Name
#  [deg]    [deg]    ['] [deg]  [deg]                   [']
186.8624 -62.8153    6.1  53.2  -28.0  -1.1028  -1.9    6.3	GX 301-2                      
264.8770 -44.4279    5.3  47.9   32.9  -1.4674  -2.2    5.9	4U 1735-44                    
332.4278 -21.8234    3.0  42.4  120.9   2.7713   3.9 ------	UNKNOWN                       
249.4250 -44.6232    3.0  54.1   21.3   3.9331   3.9 ------	UNKNOWN                       
  6.6332 -29.9270    2.7  35.5  171.3   1.1076   4.2 ------	UNKNOWN                       
 72.6127 -55.7787    4.7  41.0  -98.2   2.0539   2.5 ------	UNKNOWN

Plot creation:
Fri Oct 26 17:32:56 EDT 2018