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Catalogue XRT results for GRB 180618A

Data were analysed using HEASOFT version 6.32

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Summary Information

RA:11h 19m 45.94sLC breaks:1
Dec:+73° 50′ 14.3′′LC type:One-break, shallow first.
Err:1.5′′NH,intr.:2.53×1021 cm-2
Gal long:131.289RedshiftUnknown
Gal lat:41.770Γ2.2
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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 180618A

Fit Details

Nbreaksχ2dofCommentsImage
0266104Image of this fit
1127102Break required.

(5.48e-15 % probability of chance improvement).
This is the best fit.
Image of this fit
2108100Break significance <4-σ
(0.03 % probability of chance improvement)
Image of this fit
399.798Break significance <4-σ
(6.34e-03 % probability of chance improvement)
Image of this fit

There are no flares ignored from this fit.

The best-fitting light curve has 1 break.

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.

α10.77 (+0.17, -0.19)
Tb,1161 (+20, -15) s
α21.74 (+0.05, -0.05)

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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

phase1 spectrum (T0 + 83 to 160 s)

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Plots to download

WT mode spectrum of GRB 180618A

WT mode. Mean photon arrival: T0+119 s

NH (Galactic)4.44 × 1020 cm-2
NH (intrinsic)2.2 (+0.5, -0.5) × 1021 cm-2
z of absorber0
Photon index1.82 (+0.12, -0.12)
Flux (0.3-10 keV)
(Observed)
8.2 (+0.6, -0.6) × 10-10 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
1.09 (+0.06, -0.06) × 10-9 erg cm-2 s-1
Counts to flux (obs)3.94 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.25 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
388.41 (439)
Spectrum exposure76 s

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phase2 spectrum (T0 + 160 to 224278 s)

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WT and PC mode spectra of GRB 180618A

WT mode. Mean photon arrival: T0+247 s

NH (Galactic)4.44 × 1020 cm-2
NH (intrinsic)2.0 (+0.5, -0.4) × 1021 cm-2
z of absorber0
Photon index1.96 (+0.12, -0.12)
Flux (0.3-10 keV)
(Observed)
2.91 (+0.21, -0.20) × 10-10 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
4.05 (+0.23, -0.23) × 10-10 erg cm-2 s-1
Counts to flux (obs)3.56 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)4.95 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
417.58 (439)
Spectrum exposure216 s

PC mode. Mean photon arrival: T0+5511 s

NH (Galactic)4.44 × 1020 cm-2
NH (intrinsic)2.74 (+1.01, -0.89) × 1021 cm-2
z of absorber0
Photon index2.26 (+0.25, -0.24)
Flux (0.3-10 keV)
(Observed)
1.54 (+0.20, -0.17) × 10-12 erg cm-2 s-1
Flux (0.3-10 keV)
(Unabsorbed)
2.6 (+0.3, -0.3) × 10-12 erg cm-2 s-1
Counts to flux (obs)3.26 × 10-11 erg cm-2 ct-1
Counts to flux (unabs)5.62 × 10-11 erg cm-2 ct-1
W-stat (dof)
What's this?
230.62 (256)
Spectrum exposure25.1 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 180618A 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 One-break, shallow first light curves. GRB 180618A 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.

One-break, shallow first
Shallow phase
One-break, shallow first
Steep phase
Comparison of One-break, shallow first, shallow phase closuresComparison of One-break, shallow first, steep phase closures

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