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Last modified: December 2009

AHELP for CIAO 4.2


Context: tools


Compute image that gives indication of pileup.


pileup_map  infile outfile [clobber] [verbose]


Computes a rough estimate of the amount of pileup. The output image is the number of counts per ACIS frame. Details on how the tool works are available in the Pile-up Fractions and Count Rates document [PDF]. The following table is from that memo; note that the "Count rate per sec" column assumes a standard frame time of 3.2 s. These numbers are meant only to serve as a guide.

Relationship between Pileup Fraction and Count Rate

Pileup Fraction Count rate per frame Count rate per sec
1% 0.02 0.007
5% 0.1 0.03
10% 0.2 0.07

In a severely piled-up case, the counts image can form a 'crater' where the apparent pileup is low. There should be a halo around this crater with a larger pileup indicator.


pileup_map img.fits pileup.fits

Creates the pileup image based on the input img.fits file.


name type ftype def min max reqd
infile file input       yes
outfile file output       yes
clobber boolean   no      
verbose integer   0 0 5  

Detailed Parameter Descriptions

Parameter=infile (file required filetype=input)

Input counts image

The input image must be binned by 1 for the algorithm to work. The recommended image size is ~2048x2048. It is recommended also that the tool be run on a chip-by-chip basis, to avoid incorrect results for cases where the observation experienced a number of dropped frames, as is often the case where pileup is a concern.

Users may use the sky FOV file to create an image of the desired chip, e.g.

dmcopy "evt2.fits[ccd_id=3,sky=region(fov.fits)][bin sky=::1]" img.fits

See "ahelp skyfov" for more information.

Parameter=outfile (file required filetype=output)

The output image

The output image has units of counts/frame.

Parameter=clobber (boolean default=no)

Clobber outfile

Remove outfile if it already exists?

Parameter=verbose (integer default=0 min=0 max=5)

The tool chatter level

Verbose can be from 0 to 5, generating different amounts of debugging output.


See the bugs page for this tool on the CIAO website for an up-to-date listing of known bugs.

See Also

dmappend, dmcontour, dmellipse, dmfilth, dmimg2jpg, dmimgadapt, dmimgblob, dmimgcalc, dmimgfilt, dmimghist, dmimglasso, dmimgpick, dmimgpm, dmimgproject, dmimgreproject, dmimgthresh, dmmaskbin, dmmaskfill, dmnautilus, dmregrid, dmregrid2, dmstat, evalpos, get_sky_limits

Last modified: December 2009