Analysis for Ground-detected GRB170524B
Analysis Summary
Notes:
- 1) No attempt has been made to eliminate the non-significant decimal places.
- 2) This is a special analysis for ground-detected GRB. The event data duration is likely to be shorter than the burst duration. In such cases, the burst durations are found using the quad-rate data, and spectral analyses are only available for event data range.
- 3) When spectral analysis covers slew times, the analysis uses an average response file made by some sub-response-files with a 5-s time interval during slew times.
==========================================================================
BAT GROUND-DETECTED GRB DATA PROCESSING REPORT
(This burst occurred during telescope slew)
Process Script Ver: batgrbproduct v2.46
Process Start Time: Thu May 25 09:50:58 EDT 2017
Host Name: bat1
Current Working Dir: /local/data/bat1/alien/Swift_3rdBATcatalog/event/batevent_reproc/GRB170524B
======================================================================
Trigger: 00753445 Segment: 006
BAT Trigger Time: 517315259.2
UTC: 2017-05-24T10:40:40.20 [includes UTCF correction]
Where From?: Ground analysis (best_duration.txt)
NOTE: BAT trigger time for ground-detected burst during slew is the T100 start time.
Analysis Position: [ source = GCN ]
RA: 90.8641 Dec: -17.0864 [deg; J2000]
Refined Position: [ source = BAT mosaic image ]
RA: 90.8655956209218 Dec: -17.080680000449 [deg; J2000]
{ 06h 03m 27.7s , -17d -4' -50.4" }
+/- 0.664203320764 [arcmin] (estimated 90% radius based on SNR)
SNR: 54.5796631666
Angular difference between the GCN position (ra=90.8641, dec=-17.0864 deg) and this refined position is 0.354 arcmin
Partial Coding Fraction: Unavailable because the burst occurred during slew.
Duration
T90: 46.4000000357628 +/- 1.6
Measured from: 0
to: 46.4 [s; relative to TRIGTIME]
T50: 27.2000000476837 +/- 1.6
Measured from: 4.8
to: 32 [s; relative to TRIGTIME]
=== 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 5.97e-07 1.36e-06 2.44e-06 1.04e-05 6.64e-06 1.48e-05 erg/cm2
Error 4.16e-08 5.55e-08 8.31e-08 8.40e-07 2.16e-07 8.68e-07 erg/cm2
Peak flux Power-law 6.62e-04 6.89e-03 7.58e-02 8.02e+00 3.38e-01 7.95e+00 ph/cm2/s
Error -------- -------- -------- -------- -------- -------- ph/cm2/s
Fluence Cutoff-PL 3.47e-07 4.62e-07 4.74e-07 1.11e-06 1.58e-06 2.42e-06 erg/cm2
Error 4.96e-08 7.43e-08 5.41e-08 -------- 2.07e-07 1.91e-07 erg/cm2
Peak flux Cutoff-PL 1.99e+00 2.53e+00 2.34e+00 3.79e+00 8.16e+00 1.08e+01 ph/cm2/s
Error -------- -------- -------- -------- 3.74e-01 8.78e-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 1.152 0.058 - - 1.35e-02 4.37e-04 73.490 57
CPL 0.938 0.179 296.3 -86.1 1.67e-02 3.73e-03 70.910 56
The chi2 of BB fit is Chi-Squared which shows a significant improvement in the fit over a PL.
Check the BB fit.
=== 1-s peak spectral analysis ===
Model Ph_index Ph_90err Epeak Epeak_90err Norm Nomr_90err chi2 dof
PL 1.109 0.076 - - 7.02e-02 2.86e-03 43.020 57
CPL 1.104 0.200 9998.8 0.0 7.05e-02 1.16e-02 43.030 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
=== Table of the duration information ==
Value tstart tstop
T100 49.600 0.000 49.600
T90 46.400 0.000 46.400
T50 27.200 4.800 32.000
Peak 1.000 6.700 7.700
Image
Note1: The mosaic image is made with timebin = 0.2 s; energybin = 15-350 keV
Note2: The mosaic image uses Galactic coordinate.
#RAcent DECcent POSerr Theta Phi Peak_Cts SNR Name
90.866 -17.081 0.001 38.131 25.491 0.183 54.580 UNKNOWN
Image time interval: 0.000 to 49.600 [sec]
Lightcurves
Notes:
- 1) 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.
- 2) 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 (for the best duration plot, slew times are marked by green arrows).
- 3) For lightcurves in unit of count rate, time of each bin is in the middle of the bin.
Best duration plot
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
8 ms binning
From T100_start-3 s to T100_start+3 s
2 ms binning
From T100_start-1 s to T100_start+1 s
SN=5 or 10 sec. binning (whichever binning is satisfied first)
SN=5 or 10 sec. binning (T < 200 sec)
Spectral Evolution
Spectra
Notes:
- 1) The fitting includes the systematic errors.
- 2) For long bursts, a spectral fit of 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.
- 4) For short bursts (T90<1sec), the specrtum is also fit with Blackbody, OTTB, and Double Blackbody.
Time averaged spectrum fit using the pre-slew DRM
Power-law model
Time interval is from 1.800 sec. to 49.600 sec.
Spectral model in power-law:
------------------------------------------------------------
Parameters : value lower 90% higher 90%
Photon index: 1.15249 ( -0.0583359 0.0578185 )
Norm@50keV : 1.35223E-02 ( -0.000437508 0.000435985 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 73.49 using 59 PHA bins.
# Reduced chi-squared = 1.289 for 57 degrees of freedom
# Null hypothesis probability = 6.975279e-02
Photon flux (15-150 keV) in 47.8 sec: 1.57745 ( -0.05472 0.05488 ) ph/cm2/s
Energy fluence (15-150 keV) : 6.64965e-06 ( -2.15548e-07 2.15941e-07 ) ergs/cm2
Cutoff power-law model
Time interval is from 1.800 sec. to 49.600 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters : value lower 90% higher 90%
Photon index: 0.938330 ( -0.239752 0.117274 )
Epeak [keV] : 296.333 ( -124.223 -296.333 )
Norm@50keV : 1.66664E-02 ( -0.00321034 0.00424021 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 70.91 using 59 PHA bins.
# Reduced chi-squared = 1.266 for 56 degrees of freedom
# Null hypothesis probability = 8.654024e-02
Photon flux (15-150 keV) in 47.8 sec: 1.55698 ( -0.05851 0.05871 ) ph/cm2/s
Energy fluence (15-150 keV) : 1.58179e-06 ( -2.28819e-07 1.84363e-07 ) ergs/cm2
Band function
Time interval is from 1.800 sec. to 49.600 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] : 21.6274 ( )
R^2/D10^2 : 5.61615E-02 ( )
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared = 232.59 using 59 PHA bins.
# Reduced chi-squared = 4.0806 for 57 degrees of freedom
# Null hypothesis probability = 4.497114e-23
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 2.342e-07 1.563e-08
25- 50 1.226e-06 6.620e-08
50-150 4.281e-06 2.008e-07
15-150 5.741e-06 2.055e-07
Thermal bremsstrahlung (OTTB)
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters : value Lower 90% Upper 90%
kT [keV] : 199.363 ( )
Norm : 6.82958 ( )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 222.04 using 59 PHA bins.
# Reduced chi-squared = 3.8954 for 57 degrees of freedom
# Null hypothesis probability = 2.493312e-21
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 8.129e-07 2.772e-08
25- 50 1.564e-06 5.378e-08
50-150 3.430e-06 1.152e-07
15-150 5.806e-06 2.151e-07
Double BB
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters : value Lower 90% Upper 90%
kT1 [keV] : 9.07963 (-1.27583 1.40978)
R1^2/D10^2 : 0.535393 (-0.183349 0.321128)
kT2 [keV] : 35.3878 (-4.39616 6.85866)
R2^2/D10^2 : 9.66926E-03 (-0.00416275 0.00542942)
------------------------------------------------------------
#Fit statistic : Chi-Squared = 74.31 using 59 PHA bins.
# Reduced chi-squared = 1.351 for 55 degrees of freedom
# Null hypothesis probability = 4.244704e-02
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 4.940e-07 6.317e-08
25- 50 1.423e-06 1.240e-07
50-150 4.695e-06 5.014e-07
15-150 6.612e-06 6.573e-07
Peak spectrum fit
Power-law model
Time interval is from 0.000 sec. to 0.000 sec.
Spectral model in power-law:
------------------------------------------------------------
Parameters : value lower 90% higher 90%
Photon index: 1.10900 ( -0.0757386 0.0754133 )
Norm@50keV : 7.01692E-02 ( -0.00286245 0.00286098 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 43.02 using 59 PHA bins.
# Reduced chi-squared = 0.7547 for 57 degrees of freedom
# Null hypothesis probability = 9.148571e-01
Photon flux (15-150 keV) in 1 sec: 0.337830 ( ) ph/cm2/s
Energy fluence (15-150 keV) : 7.31627e-07 ( -3.3266e-08 3.33705e-08 ) ergs/cm2
Cutoff power-law model
Time interval is from 0.000 sec. to 0.000 sec.
Spectral model in the cutoff power-law:
------------------------------------------------------------
Parameters : value lower 90% higher 90%
Photon index: 1.10387 ( -0.216044 0.18327 )
Epeak [keV] : 9998.78 ( -9998.82 -9998.82 )
Norm@50keV : 7.05431E-02 ( -0.00286768 0.0202584 )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 43.03 using 59 PHA bins.
# Reduced chi-squared = 0.7684 for 56 degrees of freedom
# Null hypothesis probability = 8.981669e-01
Photon flux (15-150 keV) in 1 sec: 8.15836 ( -0.38661 0.36217 ) ph/cm2/s
Energy fluence (15-150 keV) : 1.61128e-07 ( -2.48455e-08 1.92942e-08 ) ergs/cm2
Band function
Time interval is from 0.000 sec. to 0.000 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] : 20.8249 ( )
R^2/D10^2 : 0.331891 ( )
(R is the radius in km and D10 is the distance to the source in units of 10 kpc)
------------------------------------------------------------
#Fit statistic : Chi-Squared = 170.87 using 59 PHA bins.
# Reduced chi-squared = 2.9977 for 57 degrees of freedom
# Null hypothesis probability = 2.646006e-13
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 2.729e-08 2.325e-09
25- 50 1.395e-07 8.350e-09
50-150 4.507e-07 3.095e-08
15-150 6.175e-07 3.405e-08
Thermal bremsstrahlung (OTTB)
Spectral model: thermal bremsstrahlung
------------------------------------------------------------
Parameters : value Lower 90% Upper 90%
kT [keV] : 199.363 ( )
Norm : 33.5326 ( )
------------------------------------------------------------
#Fit statistic : Chi-Squared = 141.82 using 59 PHA bins.
# Reduced chi-squared = 2.4881 for 57 degrees of freedom
# Null hypothesis probability = 3.523716e-09
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 8.350e-08 3.735e-09
25- 50 1.606e-07 6.850e-09
50-150 3.523e-07 1.585e-08
15-150 5.964e-07 2.720e-08
Double BB
Spectral model: bbodyrad<1> + bbodyrad<2>
------------------------------------------------------------
Parameters : value Lower 90% Upper 90%
kT1 [keV] : 8.02758 (-1.41126 1.54432)
R1^2/D10^2 : 4.16636 (-1.73793 3.77327)
kT2 [keV] : 35.8795 (-5.24467 8.2569)
R2^2/D10^2 : 5.22228E-02 (-0.02414 0.0341133)
------------------------------------------------------------
#Fit statistic : Chi-Squared = 46.78 using 59 PHA bins.
# Reduced chi-squared = 0.8505 for 55 degrees of freedom
# Null hypothesis probability = 7.770901e-01
Energy Fluence 90% Error
[keV] [erg/cm2] [erg/cm2]
15- 25 5.804e-08 1.061e-08
25- 50 1.474e-07 1.945e-08
50-150 5.349e-07 8.315e-08
15-150 7.404e-07 9.695e-08
Webpage updated on:
Thu May 25 13:08:06 EDT 2017