.help grpselect May00 noao.digiphot.daophot
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NAME
grpselect -- select groups from a group file by group size
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USAGE
grpselect ingroupfile outgroupfile min_group max_group
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PARAMETERS
.ls ingroupfile
The list of input group files. Ingroupfile must have been written by the
DAOPHOT PSF, GROUP, or NSTAR tasks. Ingroupfile may be an APPHOT/DAOPHOT text
database or an STSDAS table.
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.ls outgroupfile
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 \fIingroupfile\fR.
.le
.ls min_group
The minimum group size to select from the input group file(s).
.le
.ls max_group
The maximum group size to select from the input group file(s).
.le
.ls 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".
.le
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DESCRIPTION
GRPSELECT creates a new GROUP file \fIoutgroupfile\fR by selecting groups from
the input GROUP file \fIingroupfile\fR within a range of group sizes specified
by \fImin_group\fR and \fImax_group\fR. If \fIingroupfile\fR is a DAOPHOT text
database, \fIoutgroupfile\fR is a text database. Conversely if \fIingroupfile\fR
is a DAOPHOT STSDAS table database, \fIoutgroupfile\fR is an STSDAS table 
database.

A typical use for GRPSELECT is to create a new database containing only groups
which are less than the value of the \fImaxgroup\fR 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 \fImaxgroup\fR, rerunning GROUP on the output with a less
stringent value of the DAOPARS parameter task \fIcritovlap\fR to reduce the
group sizes and inputting the result into NSTAR.

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EXAMPLES

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.

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

.fi

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. 

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

.fi

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TIME REQUIREMENTS
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BUGS
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SEE ALSO
group
.endhelp
