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Catalogue XRT results for GRB 191221B

Data were analysed using HEASOFT version 6.32

Summary Information

RA:	10h 19m 19.20s	LC breaks:	5
Dec:	-38° 09′ 27.2′′	LC type:	Canonical.
Err:	1.4′′	N_H,intr.:	5.79×10¹⁶ cm^-2
Gal long:	272.731	Redshift	1.148
Gal lat:	15.636	Γ	1.9

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Jump to: Light curve | Spectra | Compare to other bursts.

If you use any of these data, please cite Evans et al. (2009), which describes how these products were created (see the usage policy for more information).

Light curve

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This light curve comes from the light curve repository (if you use it, please cite Evans et al [2007, 2009]. Flares, marked by cross-hatched regions, are identified automatically, but may have been manually corrected. These are excluded from the fit. Any power-law breaks added to the fit must be required at the 4-σ level (according to an f-test) to be included in the best-fit. Details of all fits attempted are given below the plot. For more information see the light curve fitting documentation.

Fit Details

N_breaks	χ²	dof	Comments
0	2573	756
1	1670	754	Break required. (2.01e-69 % probability of chance improvement)
2	935	752	Break required. (2.02e-93 % probability of chance improvement)
3	847	750	Break required. (8.39e-15 % probability of chance improvement)
4	804	748	Break required. (2.85e-07 % probability of chance improvement)
5	762	746	Break required. (2.07e-07 % probability of chance improvement). This is the best fit.

There are 2 flares excluded from the fit:

74.2—100 s
850—927 s

The best-fitting light curve has 5 breaks.

Click on the number of breaks in the table to the right to change which fit is plotted above and detailed below.

Currently showing the best fit.

α₁	1.35 (+0.04, -0.04)
T_b,1	394 (+23, -33) s
α₂	0.67 (+0.10, -0.09)
T_b,2	785 (+24, -48) s
α₃	-0.8 (+0.5, -0.7)
T_b,3	953 (+36, -49) s
α₄	1.42 (+0.04, -0.04)
T_b,4	1.19 (+0.07, -0.52) × 10⁴ s
α₅	-1.50 (+0.00, +2.52)
T_b,5	1.77 (+1.40, -0.10) × 10⁴ s
α₆	1.902 (+0.107, -0.096)

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Spectra

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Spectra have been created for each power-law segment in the best fitting light curve (shown above). Times of flaring have not been removed, however this makes little difference to most spectra (see Fig 7/8c of Evans et al. 2009). For more information see the time-resolved spectroscopy documentation.

phase1 spectrum (T0 + 90 to 394 s)

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WT mode. Mean photon arrival: T0+204 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	5 (+34, -5) × 10¹⁹ cm^-2
z of absorber	1.148
Photon index	2.095 (+0.030, -0.023)
Flux (0.3-10 keV) (Observed)	2.00 (+0.03, -0.04) × 10^-9 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	2.47 (+0.04, -0.03) × 10^-9 erg cm^-2 s^-1
Counts to flux (obs)	3.10 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	3.83 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	656.54 (698)
Spectrum exposure	304 s

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phase2 spectrum (T0 + 394 to 785 s)

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WT mode. Mean photon arrival: T0+574 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	0 (+1.65 × 10²⁰, -0) cm^-2
z of absorber	1.148
Photon index	2.071 (+0.031, -0.030)
Flux (0.3-10 keV) (Observed)	6.81 (+0.17, -0.13) × 10^-10 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	8.35 (+0.17, -0.16) × 10^-10 erg cm^-2 s^-1
Counts to flux (obs)	3.12 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	3.83 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	654.14 (600)
Spectrum exposure	390 s

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phase3 spectrum (T0 + 785 to 952 s)

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WT mode. Mean photon arrival: T0+871 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	8 (+10, -8) × 10²⁰ cm^-2
z of absorber	1.148
Photon index	1.98 (+0.07, -0.07)
Flux (0.3-10 keV) (Observed)	6.60 (+0.31, -0.29) × 10^-10 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	8.08 (+0.30, -0.29) × 10^-10 erg cm^-2 s^-1
Counts to flux (obs)	3.29 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	4.03 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	446.21 (497)
Spectrum exposure	167 s

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phase4 spectrum (T0 + 952 to 6816 s)

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WT mode. Mean photon arrival: T0+1155 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	1.0 (+0.6, -0.6) × 10²¹ cm^-2
z of absorber	1.148
Photon index	2.01 (+0.05, -0.05)
Flux (0.3-10 keV) (Observed)	5.09 (+0.16, -0.15) × 10^-10 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	6.30 (+0.16, -0.16) × 10^-10 erg cm^-2 s^-1
Counts to flux (obs)	3.26 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	4.04 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	539.32 (603)
Spectrum exposure	447 s

PC mode. Mean photon arrival: T0+5768 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	1.2 (+1.7, -1.2) × 10²¹ cm^-2
z of absorber	1.148
Photon index	1.83 (+0.12, -0.12)
Flux (0.3-10 keV) (Observed)	6.3 (+0.5, -0.5) × 10^-11 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	7.4 (+0.5, -0.4) × 10^-11 erg cm^-2 s^-1
Counts to flux (obs)	3.67 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	4.35 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	308.05 (352)
Spectrum exposure	2.0 ks

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phase5 spectrum (T0 + 12344 to 12861 s)

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PC mode. Mean photon arrival: T0+12606 s

N_H (Galactic)	8.63 × 10²⁰ cm^-2
N_H (intrinsic)	0 (+2.07 × 10²¹, -0) cm^-2
z of absorber	1.148
Photon index	1.79 (+0.25, -0.11)
Flux (0.3-10 keV) (Observed)	2.6 (+0.4, -0.4) × 10^-11 erg cm^-2 s^-1
Flux (0.3-10 keV) (Unabsorbed)	3.0 (+0.3, -0.3) × 10^-11 erg cm^-2 s^-1
Counts to flux (obs)	3.65 × 10^-11 erg cm^-2 ct^-1
Counts to flux (unabs)	4.21 × 10^-11 erg cm^-2 ct^-1
W-stat (dof) What's this?	151.63 (163)
Spectrum exposure	516 s

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phase6 spectrum (T0 + 9223372036854775807 to -471493102 s)

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Comparison with other bursts

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Parameter distributions

The plots below show the probability density functions of the temporal and time-averaged spectral parameters for all GRBs, with the data for GRB 191221B shown on in colour. Click the images for larger versions.

For all plots, the solid vertical lines mark the values for this GRB, and the dashed lines the 1-σ uncertainties. For α and T_b, the colour changes for each phase. For the spectral parameters, the WT fits are shown in blue and the PC in red. These figures correspond to Figs. 5,6, 7a and 8a of Evans et al. (2009). See the PDF documentation for more information.

Temporal indices	Break Times	N_H	Spectral indices

Closure Relationships

The plots below show (α, β) scatter plots for each phase of all Canonical light curves. GRB 191221B is shown in colour; where multiple points appear in a given phase (e.g. WT and PC mode spectra for that phase), the different colours refer to different spectra. α and β are the temporal and spectral energy power-law indices respectively. The shaded regions mark those allowed by the standard closure relationships. These figures correspond to Fig. 10 of Evans et al. (2009). See the closure relationship documentation for more information.

Canonical Steep phase	Canonical Plateau	Canonical 'Normal'	Canonical Post jet-break

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