Gill's collaboration with Kapteyn on the Cape Photographic
Durchmusterung (CPD) and subsequent repeat observations had led to the discovery of two "star streams", or preferential groups of proper motions, shared by certain stars [now known to be a reflection of halo and disc populations or old and young stars].
The Cordoba
Durchmusterung published, containing 580,000 stars.
The variability of T Ursae Majoris was discovered in 1860 by the astronomers at Bonn Observatory in Germany who were compiling the great Bonner
Durchmusterung star catalog and atlas.
The immediate outcome was the Cape Photographic
Durchmusterung which gives the approximate positions and brightness of nearly half a million southern stars.
Among the most important 19th century surveys were the Bonner
Durchmusterung (BD) of Argelander and the Cape Photographic
Durchmusterung (CPD) of Gill and Kapteyn.
The month before his discovery of V Cas, he had also reported that another star listed in the Bonner
Durchmusterung as being of magnitude 8.7 was apparently 'missing'.
This star's variability was discovered at Bonn Observatory in Germany in the mid-19th century while astronomers were compiling the great Bonner
Durchmusterung star catalog.
Pickering noted in the publication of his A
Durchmusterung of Variable Stars, that the value of visual observations of variable stars was no longer centred on the individual's attention to a single star, but on the recruitment of many observers who were able to observe as many stars as possible.
The first photographically produced catalogue of stars, the Cape Photographic
Durchmusterung (CPD), was the brainchild of David Gill, Her Majesty's Astronomer at the Cape in the years 1879-1907.
150 ya, in 1859, publication of the Bonner
Durchmusterung began.
The resulting catalog, the Cape Photographic
Durchmusterung (CPD), contained positions and magnitude estimates for 454,875 stars.
One had to select stars from the BD (Bonner
Durchmusterung 1855.0) charts, of which Waterfield had a rare set, and then hope to find reliable data for them in a catalogue.