Most tables available through this web site have an integer "snapnum" column.
This column indexes the output snapshots from the different simulations described
here.
Each snapshot corresponds to a different redshift. And though the redshifts are generally also stored in the catalogues,
it is in general MUCH more efficient to base queries for specific snapshots on the snapnum column.
When indexes have been defined for speeding up requests for particular snapshots, almost always the snapnum column
has been used.
The relation between snapnum and redshift varies between simulations, and also between original versions of the
catalogues and their counterparts scaled to different cosmologies.
This database contains the following tables describing these relations:
 MR: snapshots from original Millennium and milliMillennium simulations.
Equivalent to millimil..Snapshots and MField..Snapshots
 MRII: snapshots from original MillenniumII and miniMillenniumII simulations.
Equivalent to MillenniumII..Snapshots
 MR7: snapshots from WMAP7Millennium simulation
 MRscWMAP7: snapshots from Millennium scaled to WMAP7 cosmology. NOTE the last snapshot (63) corresponds to
negative redshift, i.e. is in the future!
Redshift 0 corresponds to snapshot 53.
 MRIIscWMAP7: snapshots from MillenniumII scaled to WMAP7 cosmology. NOTE the last snapshot (67) corresponds to negative redshift, i.e. is in the future!
Redshift 0 corresponds to snapshot 57.
All tables have the same design:
column  type  UCD  unit  description 
snapnum  integer    The index of the snapshot in the list of outputs orderd by time. 
a  real    The scale factor t the time of this snapshot 
z  real    The redshift in full precision 
Hz  real   km/s/Mpc  The Hubble parameter at the time of this snapshot 
lookBackTime  real   10^{9} years  The lookback time corresponding to the snapshot 
To find the relation between redshift and snapnum simply run a query like the following:
select *
from snapshots..MRscWMAP7
