Surface brightness selection
Use mean SB above detection isophote.
SB limit varies from field to field.
Approximate mean SB limit 24.3 mag arcsec-2.
Objects without z’s have faint mags, but are not esp. LSB.
SB limit varies with absolute magnitude: e.g. at bJ=19.45, more luminous galaxies have higher z and larger (1+z)4 SB and K(z) corrections.