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            pileup: CCD pile-up model for Chandra

CCD pile-up model used for brightish point sources observed by Chandra. This is an implementation of the fast pile-up algorithm proposed by John Davis (see http://space.mit.edu/~davis/papers/pileup2001.pdf). The frame time and maximum number of photons to pile up should be fixed. The grade morphing is expressed through a single parameter, alpha, which should be left as a free parameter. This model should be considered in beta test. Note that to calculate fluxes etc. for the model you must remove the pileup component. The pile-up model is similar to the operation of the convolution models, differing only in the treatment of the detector efficiency during the convolution.

par1

frame time (in seconds)

par2

maximum number of photons to pile up

par3

grade correction for single photon detection

par4

grade morphing parameter (good grade fraction is assumed proportional to par4p-1 where p is the number of piled photons)

par5

PSF fraction. Only this fraction will be treated for pile-up

par6

Number of regions. The counts to be piled-up will be distributed among par6 regions, which will be piled-up independently.