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grpselect noao.digiphot.daophot



grpselect -- select groups from a group file by group size


grpselect ingroupfile outgroupfile min_group max_group


The list of input group files. Ingroupfile must have been written by the DAOPHOT PSF, GROUP, or NSTAR tasks. IngroupfileR may be an APPHOT/DAOPHOT text database or an STSDAS table.
The list of output group files. There must be one output group file for every input group file. Outgroupfile has the same file type as ingroupfile .
The minimum group size to select from the input group file(s).
The maximum group size to select from the input group file(s).
verbose = ")_.verbose"
Print messages about the progress of the task? Verbose may be set to the value of the daophot package parameter (the default), "yes", or "no".


GRPSELECT creates a new GROUP file outgroupfile by selecting groups from the input GROUP file ingroupfile within a range of group sizes specified by min_group and max_group . If ingroupfile is a DAOPHOT text database, outgroupfile is a text database. Conversely if ingroupfile is a DAOPHOT STSDAS table database, outgroupfile is an STSDAS table atabase.

A typical use for GRPSELECT is to create a new database containing only groups which are less than the value of the maxgroup parameter in the DAOPARS task for direct input into the NSTAR task. The remaining stars in the larger groups are reduced by running GRPSELECT once more, selecting only groups greater than maxgroup , rerunning GROUP on the output with a less stringent value of the DAOPARS parameter task critovlap to reduce the group sizes and inputting the result into NSTAR.


1. Select groups with between 1 and 70 stars from the GROUP task output file ypix.grp.1 and write them into a new file named ypixsmall.grp.

    da> grpselect ypix.grp.1 ypixsmall.grp 1 70

2. Select groups larger than 70 from the same input group file and rerun group with a new value of the critoverlap parameter on the results.

    da> grpselect ypix.grp.1 ypixlarge.grp 71 400
    da> group dev$ypix ypixlarge.grp ypix.psf.1 default crit=5.0





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