File Formats

1: Mock Catalogues

The catalogue files are (bigendian) fortran unformatted files with the following record structure.

write(10) ndummy,n
write(10) zmax_cat
write(10) ismc
write(10) xc,yc,zc,basis(3,3),mockseed,vxc,vyc,vzc
write(10) sigma_8,omega_0,lambda_0
write(10) (x(i),i=1,n)
write(10) (y(i),i=1,n)
write(10) (z(i),i=1,n)
write(10) (zh(i),i=1,n)
write(10) (mag(i),i=1,n)
write(10) (zhmax(i),i=1,n)
write(10) (id(i),i=1,n)

ndummy=0,ismc=2 Both of these values can be ignored.

n The number of galaxies in the catalogue.

zmax_cat The highest redshift in the galaxy catalogue.

xc,yc,zc,basis(3,3),mockseed,vxc,vyc,vzc This record can be skipped. It contains information relating the catalogue to the N-body simulation from which it was constructed

sigma_8,omega_0,lambda_0 The cosmological model parameters.

x(i),y(i) and z(i) These vectors contain the cartesian x,y,z redshift space postions of the catalogue galaxies.
The units are such that zz(i) = sqrt(x(i)^2+y(i)^2+z(i)^2) is the galaxy redshift.
For the 2dF catalogues: RA and Dec are then given by sin(dec)=z/zz tan(ra)=y/x
For SDSS the same relations yield as SDSS latitude and longitude sin(lat)=z/zz tan(long)=y/x

zh(i) Is the redshift the galaxy would have if it had no peculiar velocity.

mag(i) galaxy apparent magnitude B_J

zhmax(i) maximum redshift at which the galaxy would enter into the catalogue taking account of k-correction and any luminosity evolution. Thus selecting galaxies with zz(i) < zcut and zhmax(i) > zcut will produce a volume limited catalogue

id(i) particle index in orginal simulation (ignore)

2: Selection Function Files

For every mock catalogue there is a corresponding selection function file. These have the same file name as the corresponding mock catalogue except they are preceeded by "sel", e.g. sel1.2df_sgp . Each file consists of an ASCII table with the following columns

Redshift Co-moving Distance Number of Galaxies Number density

z r N(z) n(z)

Redshift	Co-moving Distance	Number of Galaxies	Number density
z	r	N(z)	n(z)

The final comment line quotes the mean surface density of galaxies per square degree at the magnitude limit of the survey.

r is the comoving distance to redshift z in Mpc/h

N(z) is the expected number of galaxies in the catalogue with redshift less than z.

n(z) is the expected galaxy number density per (Mpc/h)^3 at redshift z.

ndummy=0,ismc=2	Both of these values can be ignored.
n	The number of galaxies in the catalogue.
zmax_cat	The highest redshift in the galaxy catalogue.
xc,yc,zc,basis(3,3),mockseed,vxc,vyc,vzc	This record can be skipped. It contains information relating the catalogue to the N-body simulation from which it was constructed
sigma_8,omega_0,lambda_0	The cosmological model parameters.
x(i),y(i) and z(i)	These vectors contain the cartesian x,y,z redshift space postions of the catalogue galaxies. The units are such that zz(i) = sqrt(x(i)^2+y(i)^2+z(i)^2) is the galaxy redshift. For the 2dF catalogues: RA and Dec are then given by sin(dec)=z/zz tan(ra)=y/x For SDSS the same relations yield as SDSS latitude and longitude sin(lat)=z/zz tan(long)=y/x
zh(i)	Is the redshift the galaxy would have if it had no peculiar velocity.
mag(i)	galaxy apparent magnitude B_J
zhmax(i)	maximum redshift at which the galaxy would enter into the catalogue taking account of k-correction and any luminosity evolution. Thus selecting galaxies with zz(i) < zcut and zhmax(i) > zcut will produce a volume limited catalogue
id(i)	particle index in orginal simulation (ignore)

r	is the comoving distance to redshift z in Mpc/h
N(z)	is the expected number of galaxies in the catalogue with redshift less than z.
n(z)	is the expected galaxy number density per (Mpc/h)^3 at redshift z.