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Catalogue XRT results for GRB 180809B

Data were analysed using HEASOFT version 6.32

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Summary Information

RA:19h 58m 47.99sLC breaks:4
Dec:-15° 17′ 56.3′′LC type:Canonical.
Err:1.4′′NH,intr.:1.92×1021 cm-2
Gal long:26.296RedshiftUnknown
Gal lat:-21.655Γ1.8
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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.

Fitted light curve of GRB 180809B

Fit Details

Nbreaksχ2dofCommentsImage
073991265Image of this fit
118041263Break required.

(0.00e+00 % probability of chance improvement)
Image of this fit
212511261Break required.

(5.92e-99 % probability of chance improvement)
Image of this fit
312061259Break required.

(1.08e-08 % probability of chance improvement)
Image of this fit
411631257Break required.

(1.38e-08 % probability of chance improvement).
This is the best fit.
Image of this fit
511541255Break significance <4-σ
(0.60 % probability of chance improvement)
Image of this fit

There are 3 flares excluded from the fit:

  • 60.9—97.9 s
  • 189—306 s
  • 395—408 s

The best-fitting light curve has 4 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.

α10.26 (+0.04, -0.07)
Tb,1347 (+12, -31) s
α21.29 (+0.11, -0.18)
Tb,2493 (+91, -24) s
α30.863 (+0.024, -0.029)
Tb,32270 (+753, -772) s
α41.24 (+0.10, -0.09)
Tb,45.9 (+2.6, -2.7) × 104 s
α52.2 (+0.3, -0.3)

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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.

Jump to: phase1|phase2|phase3|phase4|phase5

phase1 spectrum (T0 + 74 to 346 s)

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Plots to download

WT mode spectrum of GRB 180809B

WT mode. Mean photon arrival: T0+216 s

NH (Galactic)1.19 × 1021 cm-2
NH (intrinsic)1.80 (+0.16, -0.16) × 1021 cm-2
z of absorber0
Photon index1.448 (+0.028, -0.028)
Flux (0.3-10 keV)
(Observed)
7.51 (+0.13, -0.13) × 10-9 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
8.95 (+0.12, -0.12) × 10-9 erg cm-2 s-1
Counts to flux (obs)5.09 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)6.06 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
838.59 (860)
Spectrum exposure272 s

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phase2 spectrum (T0 + 346 to 493 s)

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WT mode spectrum of GRB 180809B

WT mode. Mean photon arrival: T0+414 s

NH (Galactic)1.19 × 1021 cm-2
NH (intrinsic)2.38 (+0.22, -0.22) × 1021 cm-2
z of absorber0
Photon index1.82 (+0.04, -0.04)
Flux (0.3-10 keV)
(Observed)
4.00 (+0.10, -0.10) × 10-9 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
5.58 (+0.11, -0.12) × 10-9 erg cm-2 s-1
Counts to flux (obs)4.14 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.78 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
748.78 (748)
Spectrum exposure146 s

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phase3 spectrum (T0 + 493 to 1551 s)

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WT mode spectrum of GRB 180809B

WT mode. Mean photon arrival: T0+937 s

NH (Galactic)1.19 × 1021 cm-2
NH (intrinsic)2.16 (+0.12, -0.12) × 1021 cm-2
z of absorber0
Photon index1.786 (+0.023, -0.023)
Flux (0.3-10 keV)
(Observed)
1.820 (+0.024, -0.024) × 10-9 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
2.472 (+0.027, -0.027) × 10-9 erg cm-2 s-1
Counts to flux (obs)4.20 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.71 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
941.69 (853)
Spectrum exposure1.1 ks

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phase4 spectrum (T0 + 4793 to 16961 s)

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PC mode spectrum of GRB 180809B

PC mode. Mean photon arrival: T0+9300 s

NH (Galactic)1.19 × 1021 cm-2
NH (intrinsic)1.9 (+0.5, -0.5) × 1021 cm-2
z of absorber0
Photon index1.758 (+0.101, -0.098)
Flux (0.3-10 keV)
(Observed)
1.58 (+0.09, -0.09) × 10-10 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
2.11 (+0.10, -0.09) × 10-10 erg cm-2 s-1
Counts to flux (obs)4.30 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.71 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
479.45 (514)
Spectrum exposure3.0 ks

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phase5 spectrum (T0 + 125208 to 529369 s)

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PC mode spectrum of GRB 180809B

PC mode. Mean photon arrival: T0+208569 s

NH (Galactic)1.19 × 1021 cm-2
NH (intrinsic)2.1 (+1.7, -1.4) × 1021 cm-2
z of absorber0
Photon index2.2 (+0.4, -0.4)
Flux (0.3-10 keV)
(Observed)
5.6 (+1.4, -1.0) × 10-13 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
9.3 (+7.1, -1.7) × 10-13 erg cm-2 s-1
Counts to flux (obs)3.49 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.81 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
112.95 (122)
Spectrum exposure15.2 ks

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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 180809B 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 Tb, 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 indicesBreak TimesNHSpectral indices
Comparison of decay indices Comparison of light curve break times Comparison of intrinsic column densities Comparison of spectral energy indices

Closure Relationships

The plots below show (α, β) scatter plots for each phase of all Canonical light curves. GRB 180809B 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
Comparison of Canonical, steep phase closuresComparison of Canonical, plateau phase closuresComparison of Canonical, normal phase closuresComparison of Canonical, post jet-break phase closures

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