XMM-Newton Science Analysis System


psfgen (psfgen-1.2) [xmmsas_20160201_1833-15.0.0]

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Example3: create multiple PSFs

psfgen supplies a way to create multiple PSFs with different energy levels in a single call. This is useful when the user is interested in for example comparing different energy band PSFs at a particular position. To do this, supply energy with a list instead of a single value, like this:

psfgen image=source.fits output=source_psf.fits energy='600 2000 10000'

The file 'source_psf.fits' contains 4 PSFs, i.e. PSF with 600eV, PSF with 2000eV, PSF with 10000eV and their linear combination (see 10). The PSFs can be viewed using command ds9 source_psf.fits[0] source_psf.fits[1] source_psf.fits[2] source_psf.fits[3].

psfgen also allows the user the give the weightings for the linear combination via parameter weight. For example,

psfgen image=source.fits output=source_psf.fits energy='600 2000 10000' weight='0.3 0.3 0.4'

will calculate the pixels in the combination PSF using

$$p_{comb}^{i,j} = \textbf{0.3} * p_{600}^{i,j} + \textbf{0.3} * p_{2000}^{i,j} + \textbf{0.4} * p_{10000}^{i,j}$$ (1)

The default weighting is $1$ for every energy band.