Preparing the mock zCosmos catalogues

We have build mock catalogues that reproduce all the biases in slit positioning introduced by SSPOC, the slit positioning software.
The starting catalogues are 24 mocks obtained from the cosmos Millennium simulations web pages - see for more information the COSMOS light cones website, or the paper by Kitzbichler & White (2006). The cosmology adopted is Ω_m = 0.25, Ω_Λ= 0.75, Ω_b = 0.045,h = 0.73, σ₈ =0.9, n=1.

NB: for each of these mocks we applied the following correction for type2 galaxies as suggested by M. Kitzbichler:
" .... could you try to correct the observed redshift of Type 2 galaxies in this way:

z_obs=(1+z)*(1+((1+z_obs)/(1+z)-1)/sqrt(1+z))-1

What looks complicated here is simply a correction of the peculiar velocity v by a factor of 1/sqrt(1+z). This mistake happened because of an inapropriate conversion of velocities from the internal code units of the Millennium run to physical units ... "

Out of the mock catalogues we extracted catalogues of galaxies magnitude limited to I_AB<22.5 and with an error of 100 Km/s added to the observed_redshift z values (to mimic the typical error in z measurements in zCosmos survey). We will call these catalogues: complete 22.5 catalogues.

For each catalogue we then extract 2 further galaxy catalogues:

one catalogue obtained by applying SSPOC for a total of 83 pointings, corresponding to the number of pointings observed as of Dec 2006 (here is the list used).
We will call these catalogues the 10K catalogues.
one catalogue obtained by applying SSPOC for a total of 180 pointings, corresponding to the final foreseen number of pointings for zCosmos (here is the list used).
We will call these catalogues the 20K catalogues.

In the following table one can find, for each mock, the links to the 10K, the 20K and the original complete (ie magnitude limited to I_AB=22.5) galaxy catalogues.

10 K catalogues (header)	20 K catalogues (header)	Complete catalogues (header)
012_000_10K.cat	012_000_20K.cat	012_000_22.5.cat
012_001_10K.cat	012_001_20K.cat	012_001_22.5.cat
012_010_10K.cat	012_010_20K.cat	012_010_22.5.cat
012_011_10K.cat	012_011_20K.cat	012_011_22.5.cat
012_100_10K.cat	012_100_20K.cat	012_100_22.5.cat
012_101_10K.cat	012_101_20K.cat	012_101_22.5.cat
012_110_10K.cat	012_110_20K.cat	012_110_22.5.cat
012_111_10K.cat	012_111_20K.cat	012_111_22.5.cat
120_000_10K.cat	120_000_20K.cat	120_000_22.5.cat
120_001_10K.cat	120_001_20K.cat	120_001_22.5.cat
120_010_10K.cat	120_010_20K.cat	120_010_22.5.cat
120_011_10K.cat	120_011_20K.cat	120_011_22.5.cat
120_100_10K.cat	120_100_20K.cat	120_100_22.5.cat
120_101_10K.cat	120_101_20K.cat	120_101_22.5.cat
120_110_10K.cat	120_110_20K.cat	120_110_22.5.cat
120_111_10K.cat	120_111_20K.cat	120_111_22.5.cat
201_000_10K.cat	201_000_20K.cat	201_000_22.5.cat
201_001_10K.cat	201_001_20K.cat	201_001_22.5.cat
201_010_10K.cat	201_010_20K.cat	201_010_22.5.cat
201_011_10K.cat	201_011_20K.cat	201_011_22.5.cat
201_100_10K.cat	201_100_20K.cat	201_100_22.5.cat
201_101_10K.cat	201_101_20K.cat	201_101_22.5.cat
201_110_10K.cat	201_110_20K.cat	201_110_22.5.cat
201_111_10K.cat	201_111_20K.cat	201_111_22.5.cat

This link goes to a page with some technical details on the procedure adopted to create the 10K and 20K samples.

In short the steps to produce these catalogues are:

1- run SSPOC on the complete 22.5 galaxy catalogue;
2- from the output catalogues remove 3 galaxies for each mask (12 galaxies per pointing) to take into account the holes used for the centering;
3- remove a further 15% of galaxies to take into account a realistic failure rate in redshift measurement

The following two plots show a typical 10K mock produced by the procedure described above and the galaxies of our 10K catalogues (v3.1, rejecting galaxies with low quality flag for redshift measurement). The agreement of the 'geography' of the two distributions is quite good, but while the 10K mocks usually contain around 11000 galaxies our 10K catalogue contains only 8709 galaxies (even with a generous definition of 'reliable redshift'!).

In the following table are the links, for each mock cone, to the 10K and 20K catalogues obtained assuming a 100% success rate in redshift measurement. The files are called *_nofailures* and contain the same columns as the ones in the previous table.

10 K catalogues_nofailures (header)	20 K catalogues_nofailures (header)
012_000_10K_nofailures.cat	012_000_20K_nofailures.cat
012_001_10K_nofailures.cat	012_001_20K_nofailures.cat
012_010_10K_nofailures.cat	012_010_20K_nofailures.cat
012_011_10K_nofailures.cat	012_011_20K_nofailures.cat
012_100_10K_nofailures.cat	012_100_20K_nofailures.cat
012_101_10K_nofailures.cat	012_101_20K_nofailures.cat
012_110_10K_nofailures.cat	012_110_20K_nofailures.cat
012_111_10K_nofailures.cat	012_111_20K_nofailures.cat
120_000_10K_nofailures.cat	120_000_20K_nofailures.cat
120_001_10K_nofailures.cat	120_001_20K_nofailures.cat
120_010_10K_nofailures.cat	120_010_20K_nofailures.cat
120_011_10K_nofailures.cat	120_011_20K_nofailures.cat
120_100_10K_nofailures.cat	120_100_20K_nofailures.cat
120_101_10K_nofailures.cat	120_101_20K_nofailures.cat
120_110_10K_nofailures.cat	120_110_20K_nofailures.cat
120_111_10K_nofailures.cat	120_111_20K_nofailures.cat
201_000_10K_nofailures.cat	201_000_20K_nofailures.cat
201_001_10K_nofailures.cat	201_001_20K_nofailures.cat
201_010_10K_nofailures.cat	201_010_20K_nofailures.cat
201_011_10K_nofailures.cat	201_011_20K_nofailures.cat
201_100_10K_nofailures.cat	201_100_20K_nofailures.cat
201_101_10K_nofailures.cat	201_101_20K_nofailures.cat
201_110_10K_nofailures.cat	201_110_20K_nofailures.cat
201_111_10K_nofailures.cat	201_111_20K_nofailures.cat

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