3.2 Galaxy Surface Photometry

Galaxies are very complex objects whose structure, formation and evolution are far from completely understood. An essential step towards putting the study of galaxies on a quantitative basis is the measurement of their surface brightness distribution. This is a particularly difficult undertaking for several reasons, but mainly because the detector response is not perfectly uniform over the focal plane, because the sky over which galaxies are observed is never completely dark and because, particularly in ground-based telescopes, the image of a point-like source which is formed on the telescope focal plane is a spot of relatively large size.