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SynopsisCompute image that gives indication of pileup. Syntaxpileup_map infile outfile [clobber] [verbose] DescriptionComputes 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
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. Parameters
Detailed Parameter DescriptionsParameter=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=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. BugsSee the bugs page for this tool on the CIAO website for an up-to-date listing of known bugs. |
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The Chandra X-Ray
Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA. Email: cxcweb@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2004. All rights reserved. |
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