Abstract
EVERYONE will naturally wish to offer words of hearty congratulation to Sir David Gill and his able coadjutor, Prof. Kapteyn, on the completion of the Cape Durchmusterung, of which the third and last volume has recently appeared. Some twenty years since, when the capacity of celestial photography was practically an unknown factor, Sir David Gill proposed to himself to complete a survey of the southern hemisphere by means of photographic star maps. The original conception was a tolerably modest one. Sir David Gill“s idea was simply to prepare from these maps a working catalogue of stars to facilitate the meridian zone observations, after the programme of the Astronomische Gesellschaft, but “to avoid the repetition of such an arduous undertaking as Argelander's Durchmusterung as a preliminary step.” How the original plan was extended and grew, till the results fill three bulky volumes, exceeding Argelander's work both in number of stars and in accuracy of observation, he has himself told in the introduction to the first part, to which we have already referred (NATURE, vol. lvii. p. 5 13). Very rapidly has the work gone on once all preliminary difficulties were removed, and now the astronomers of the Cape and of Groningen see their work completed on a uniform plan within a moderate space of time, with an accuracy which approaches that attaching to the older so-called “Precision Catalogues,” together with the means existing for the determination in special instances of star places with even greater accuracy. For though we have spoken of the completion of the work, this is to be understood in a limited sense. The discussion of the catalogue is about to begin. Such discussion will include the examination and detection of errors in the “Precision Catalogues,” the search for, and discovery of, stars with large and unsuspected proper motions, and the formation of a catalogue of variable stars for the southern hemisphere. Further, the course of the work has disclosed the existence of a possible systematic difference of colour in stars, depending on the galactic latitude, and intimately connected with this inquiry is the investigation of the systematic corrections which should be applied to the magnitudes derived from the Cape plates to ensure one uniform system, photographically considered, or to connect the photographic and optical magnitudes. A revision conducted on such ample lines is a task of only less magnitude than that of the construction of the catalogue itself, while the importance and interest are even greater. That the same competent hands will carry such a discussion to a final issue will be the hope and the expectation of all astronomers.
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P., W. Photographic and Photometric Surveys of the Stars 1 . Nature 64, 257–259 (1901). https://doi.org/10.1038/064257c0
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DOI: https://doi.org/10.1038/064257c0