Five separate light-cone 'sky' surveys are produced by each run. Their properties are summarized in the following table -

The surveys are centered at the following locations in the original simulation cube (mapped to 0-1 interval) -

Cluster catalogs derived from a SPHERICAL OVERDENSITY method applied to the light-cone particle data. Cluster lists are found in files of the form

grpSO.d$delta_c/$model.$survey.msort$min

where

   $delta_c = { 200, 500 } is the defining density threshold 
   $model   = { tcdm, lcdm } is the cosmological model 
   $survey  = { DW, VS, MS, NO, PO/POW } is the choice of sky survey 
   $min     = { 12, 48  } is the minimum particle count of the cluster 

#    m   zred  sigma  ip     x     y     z    vx    vy     vz

   m       = number of particles (particle mass is 2.22/2.25e12/h for tcdm/lcdm)
   zred    = redshift
   sigma   = measured 1D velocity dispersion 
   ip      = parent flag (see below)
   x,y,z   = cluster location in SURVEY COORDINATES in 0-1 units 
   vx,vy,vz= physical peculiar velocity in km/s

PO/NO/DW : (0,0,0)
VS/MS : (0.5,0.5,0.5)

NO : x -> 1-x
VS : x -> mod( (x-0,5), 1 )
PO/DW/MS : no transformation required

Clusters are identified using a spherical overdensity method with the following steps:

1. measure distance to 8th nearest particle = r8
2. sort in r8 (increasing order) & identify first particle
3. center group on this particle
   1. sort neightboring particles about this center
   2. cut particle list at overdensity threshold \delta_c (1)
   3. flag particles as belonging to this group (2)
4. find next particle in r8 list not flagged as a group member
5. repeat steps 3 & 4 until max r8 is reached (3)

1. \delta_c is RELATIVE TO CRITICAL DENSITY \rho_c(z) for both LCDM and tCDM
2. particles can belong to more than one group
3. defined by comparing density constrast using r8 to \delta_c threshold

+ IPARENT flag
The issue of ovelapping clusters is handled as follows. A cluster is defined to be a parent if it is the largest of any group of clusters with which it overlaps. Isolated clusters are parents by default. The `family' criterion employed is that the threshold spheres of pair i & j overlap:
| cen_i - cen_j | <= Rvir_i + Rvir_j

Note that the center of any cluster cannot lie within the threshold radius of any cluster other than itself.

The catalog files are shortened versions of the original group finder output. The group finder processes planes of cubes in the Z-direction. Separate output files for each Z-slice are produced. These files can be made available upon request.

For each slice iz, there are three output files:

• z$iz.base : basic cluster data
• z$iz.extra : internal cluster structure data
• z$iz.iparent : list of binary values for iparent flag (see above)

#  M  {X Y Z}_c  {Vx Vy Vz V}_com  sigma1D  R  R.5 S.5  {X Y Z}_mb {X Y Z}_com

 M                = cluster mass in particles (1 particle = 2.2e12/h Msol in both models)
 {X Y Z}_c        = cluster center (1)
 {Vx Vy Vz V}_com = center-of-mass velocity components and speed (2)
 sigma1D          = one-dimensional velocity dispersion (2)
 R                = cluster radius (1)
 R.5              = ratio of half mass radius to full radius R_{1/2}/R 
 S.5              = ratio of velocity dispersions within R_{1/2} and R 
 {X Y Z}_mb       = position of most bound cluster member (1,3)
 {X Y Z}_com      = position of cluster center-of-masss (1)

1. in box units (L=1). Box is (2/3)000/h Mpc for (t/L)cdm models.
2. in km/s
3. determined using N^2 sum of potential among group members only.

#  {Rxx Rxy Rxz Ryy Ryz Rzz}  {Vxx Vxy Vxz Vyy Vyz Vzz} 

Rij = Sum_k (R-R_c)_i (R-R_c)_j / M
Vij = Sum_k (V-V_com)_i (V-V_com)_j / M
and the sum is over members k running from 1 to M.