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Catalogue XRT results for GRB 180618A
Data were analysed using HEASOFT version 6.32
Summary Information
| RA: | 11h 19m 45.94s | LC 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: | 131.289 | Redshift | Unknown |
| Gal lat: | 41.770 | Γ | 2.2 |
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
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
| Nbreaks | χ2 | dof | Comments | Image |
|---|---|---|---|---|
| 0 | 266 | 104 |  | |
| 1 | 127 | 102 | Break required. (5.48e-15 % probability of chance improvement). This is the best fit. |  |
| 2 | 108 | 100 | Break significance <4-σ (0.03 % probability of chance improvement) |  |
| 3 | 99.7 | 98 | Break significance <4-σ (6.34e-03 % probability of chance improvement) |  |
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.
| α1 | 0.77 (+0.17, -0.19) |
|---|---|
| Tb,1 | 161 (+20, -15) s |
| α2 | 1.74 (+0.05, -0.05) |
Spectra
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 + 83 to 160 s)
Download spectral files for phase1 spectrum.
Plots to download
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 absorber | 0 |
| Photon index | 1.82 (+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 exposure | 76 s |
phase2 spectrum (T0 + 160 to 224278 s)
Download spectral files for phase2 spectrum.
Plots to download
- both modes ps file
- both modes gif file
- wt mode ps file
- wt mode gif file
- pc mode ps file
- pc mode gif file
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 absorber | 0 |
| Photon index | 1.96 (+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 exposure | 216 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 absorber | 0 |
| Photon index | 2.26 (+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 exposure | 25.1 ks |
Comparison with other bursts
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 indices | Break Times | NH | Spectral 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 |
|---|---|
 |  |