1.3 Automated two-dimensional surveys since 1980

In the 1980s two centers of two-dimensional surveys became established in Cambridge and in Edinburgh in collaboration with Durham University. Both surveys use glass copies of photographic atlas plates obtained with the UK Schmidt telescope, fast flying spot-type measuring machines and fully automized reduction procedures. A third group, Muenster, has joint them recently, using the same basic material, but film copies, and a double-slit measuring machine. The large numbers of data have led to sophisticated procedures of interpretation which are discussed during this workshop. The increasing number of objects available through two-dimensional surveys with time is displayed in Fig. 9.

Figure 9. The increase in number of identified galaxies from the late 18th to the late 20th century. Open symbols: individual catalogues; filled symbols: cumulative data.