Using the code clf_group_finder_mocks_mstellar.

carmichael:GroupFinder tinker$ clf_group_finder_mocks_mstellar 
clf_group_finder_mocks_mstellar inputfile BOXSIZE [vfac] [niter_max] [NHEADER]> out

inputfile: is the ascii-formatted input file. columns need to be:
 1) x
 2) y
 3) z (all Mpc/h comoving)
 4) vx
 5) vy
 6) vz [km/s]
 7) M_stellar 
 
BOXSIZE - comoving Mpc/h
vfac - SET TO UNITY (1). 
niter_max - number of iterations for the group finder. default is 10. 
NHEADER - number of header lines in the inputfile. default is 0.
 
Notes: 
 - the z-axis is assumed to be the line of sight.
 - if the first stellar mass is <13, then the masses are assumed to be in log10 units. 
 - if all you're interested in is to get centrals, then you only need niter_max=2.

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GRoups can be found here:

http://cosmo.nyu.edu/~tinker/GROUP_FINDER/STELLAR_MASS/

where the files have names like clf_groups_MXX_XX.X_D360.[groups/prob/galdata_corr]

where MXX is the magnitude limit (ie, without the negative sign-- 18,
19, 20), XX.X is the stellar mass limit at the redshift defined by the
magnitude limit (ie, 9.4, 9.8, 10.2-- all h=1 units), and D360 is the
overdensity of the halo definition (with respect to the mean). These
are the same catalogs used in Reddick et al. You can find a plot of
the cuts in magnitude/stellar mass in Tinker, Wetzel, Conroy (fig 1;
although those catalogs are slightly different, the cuts are the
same).

The format of the files is totally kludgy-- I didn't really think
about having other people use them when I was first testing the code,
and when I got something that worked I didn't want to touch
it. Anyway,

*.groups is the group catalog itself; properties of each group. The
 format


1) foo
2) group id
3) gal id (for the central)
4) group mass 
5) group mass in the previous iteration of the finder (should be same). not relevant for you.
6) number of satellites
7) total group stellar mass
8) stellar mass of central
9) foo
10) ra (radians) of central 
11) dec of central
12) cz of central (km/s)
13) foo
14) foo

*.prob is the galaxy catalog with probability of being a satellite
 (official stats assume >0.5 is a satellite).


1) foo
2) gal id
3) group id
4) id of central galaxy
5) r-band magnitude h=1
6) P_sat (>0.5 means a satellite)
7) halo mass [Msol/h]
8) foo
9) foo
10) foo
11) projected separation of gal from central, in units of Rhalo
12) projected separation of gal in units of radians
13) angular radius of halo

*.galdata_corr are galaxy properties. This file is in the same order
 as the *.prob file

1) foo
2) gal id
3) M_r
4) M_g
5) cz [km/s]
6) Dn4000  (from MPA/JHU catalog)
7) H_delta EW (same source)
8) log sSFR (1/yr same source, but uses kcorrect stellar mass for "s")
9) stellar mass (Msol/h^2, from kcorrect)
10) ra
11) dec
12) velocity dispersion (from VAGC)
13) signal to noise of spectrum (from VAGC)
14) sersic index (from VAGC) 

Unless I have said so, all units are h=1.