The Millennium Galaxy Catalogue ( MGC ) is a deep ( \mu _ { B,lim } = 26 mag arcsec ^ { -2 } ) , wide field CCD imaging survey , covering 37.5 deg ^ { 2 } .
The MGC survey region is completely contained within the Two-degree Field Galaxy Redshift Survey ( 2dFGRS ) and the Sloan Digital Sky Survey Early Data Release ( SDSS-EDR ) .
We compare the photometry and completeness of the 2dFGRS and the SDSS-EDR with the MGC over the range 16 < B < 20 mag .
We have also undertaken a photometric comparison to SuperCosmos and the SDSS First Data Release .

We find that B _ { MGC } - B _ { 2 dF } = ( 0.035 \pm 0.005 ) mag with an uncertainty of 0.142 mag per galaxy , B _ { MGC } - B _ { SCOS } = ( 0.032 \pm 0.005 ) mag with an uncertainty of 0.108 mag , B _ { MGC } - B _ { SDSS - EDR } = ( 0.032 \pm 0.005 ) mag with an uncertainty of 0.094 mag , and B _ { MGC } - B _ { SDSS - DR 1 } = ( 0.039 \pm 0.005 ) mag with an uncertainty of 0.086 mag .
We find that high surface brightness 2dFGRS galaxies are systematically too faint , which leads to a significant scale error in magnitude .
This effect is significantly reduced with the SCOS photometry .
In the SDSS there is a weak non-linear scale error , which is negligible for faint galaxies .
LSBGs in the SDSS are systematically fainter , consistent with the relative shallowness of this survey .

We find that the 2dFGRS catalogue has ( 5.2 \pm 0.3 ) per cent stellar contamination , ( 7.0 \pm 0.4 ) per cent of objects resolved into 2 or more by the MGC and is ( 8.7 \pm 0.6 ) per cent incomplete compared to the MGC .
From our all object spectroscopic survey we find that the MGC is itself misclassifying ( 5.6 \pm 1.3 ) per cent of galaxies as stars , hence the 2dFGRS misses ( 14.3 \pm 1.4 ) per cent of the galaxy population .
The SDSS-EDR galaxy catalogue has ( 1.3 \pm 0.1 ) per cent stellar contamination and ( 5.3 \pm 1.0 ) per cent of galaxies misclassified as stars , with ( 0.18 \pm 0.04 ) per cent of objects resolved into 2 or more by the MGC and is ( 1.8 \pm 0.1 ) per cent incomplete compared to the MGC .
The total fraction of galaxies missing from the SDSS-EDR galaxy catalogue to B _ { MGC } = 20 mag , from incompleteness and misclassification is ( 7.1 \pm 1.0 ) per cent .