This file describes the file format and data structure for the DEEP2
VDM group catalog.

The file is a binary FITS table containing two HDUs.  The first HDU
contains a list of the DEEP2 galaxies that were processed through the
VDM group finder, the IDs of the groups they belong to (if any), and
various other information.  The galaxy structure tags are as follows.

   OBJNO           Unique identifier from the DEEP2 galaxy catalog
   RA              RA of this galaxy
   DEC             Dec of this galaxy
   Z               Redshift of this galaxy
   CLUSTNUM        ID of the group to which this galaxy belongs (if
		   CLUSTNUM > 100000, the galaxy is isolated.)

The second HDU contains a list of groups and various properties of the
groups.  The structure tags are as follows.

   CLUSTNUM        ID of this group
   FIELD           DEEP2 field of this group (1-4; 1 is EGS)
   RA              Mean RA of the galaxies in this group
   DEC             Mean Dec of the galaxies in this group
   Z               Mean redshift of the galaxies in this group
   VDISP           Velocity dispersion of the galaxies in this group
   N_MEMBERS       Number of DEEP2 galaxies in this group
   HIGHPURITY      1 or 0; see below.  

The HIGHPURITY tag identifies groups that were also detected in a run
of the group finder that used a more conservative set of group-finding
parameters to produce a higher-purity catalog at the expense of a
sharply lower completness.  Groups that have HIGHPURITY = 1 were
also identified in this second run and can be considered
higher-confidence detections (in an ensemble sense) than the other
groups in the catalog.