Inspecting the spectral fit residuals

What you will learn

You will learn how to use the csresspec script to inspect the spectral fit residuals.

The spatial fit residuals are only one part of the quality check, and you should also inspect the spectral fit residuals. You do this using the csresspec script.

$ csresspec components=yes
Input event list, counts cube, or observation definition XML file [events.fits] cntcube.fits
Input exposure cube file [NONE] expcube.fits
Input PSF cube file [NONE] psfcube.fits
Input background cube file [NONE] bkgcube.fits
Input model definition XML file [$CTOOLS/share/models/crab.xml] crab_results.xml
Mask data to calculate residuals in ROI? [no]
Residuals computation algorithm (SUB|SUBDIV|SUBDIVSQRT|SIGNIFICANCE) [SIGNIFICANCE]
Output residual spectrum file [resspec.fits]

This produces a FITS file resspec.fits containing the residual spectrum. Note the hidden components parameter that instructs csresspec to include the individual model components in the results file. A graphical display of the result file is shown below.

Data, model, and residuals from the spectral fit of the Crab nebula

Note

The figure was created by typing:

$ $CTOOLS/share/examples/python/show_residuals.py resspec.fits

Use the option -h to select the table to display if there are multiple observations.