The Millennium Galaxy Catalogue: The Photometric accuracy, completeness and contamination of the 2dFGRS and SDSS-EDR & DR1 datasets

Dec, 2003
23 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 349 (2004) 576
e-Print:

Citations per year

200420082012201620190246810
Abstract: (arXiv)
The Millennium Galaxy Catalogue (MGC) is a deep (μB,lim=26\mu_{\rm B,lim}=26 mag arcsec2^{-2}), wide field CCD imaging survey, covering 37.5deg2^2 and is completely contained within the 2dFGRS and SDSS-EDR. We compare the photometry and completeness of the 2dFGRS and the SDSS-EDR with the MGC. We have also undertaken a photometric comparison to SCOS and SDSS-DR1 data. We find that BMGCB2dF=0.035B_{MGC}-B_{2dF}=0.035 mag with an uncertainty of 0.142 mag per galaxy, BMGCBSCOS=0.032B_{MGC}-B_{SCOS}=0.032 mag with an uncertainty of 0.108 mag, BMGCBSDSSEDR=0.032B_{MGC}-B_{SDSS-EDR}=0.032 mag with an uncertainty of 0.094 mag, and BMGCBSDSSDR1=0.039B_{MGC}-B_{SDSS-DR1}=0.039 mag with an uncertainty of 0.086 mag. We find that high surface brightness 2dFGRS galaxies are systematically too faint. In the SDSS there is a weak non-linear scale error, which is negligible for faint galaxies. LSBGs in the SDSS are systematically fainter. We find that the 2dFGRS catalogue has 5.2% stellar contamination, 7.0% of objects are resolved into 2 or more by the MGC and is 8.7% incomplete compared to the MGC. From our all object spectroscopic survey we find that the MGC is itself misclassifying 5.6% of galaxies as stars, hence the 2dFGRS misses 14.3% of the galaxies. The SDSS-EDR galaxy catalogue has 1.3% stellar contamination and 5.3% of galaxies misclassified as stars, and is 1.8% incomplete compared to the MGC. Altogether 7.1% of the total galaxy population are missing from the SDSS-EDR catalogue from incompleteness or misclassification.
Note:
  • 23 pages, 18 figures, accepted in MNRAS