Abstract
GALACTIC CO-ORDINATES.—An interesting article on the galactic circle as a plane of reference for star places is contributed to the February number of Scientia by Dr. A. C. D. Crommelin. Following a comparison of the more familiar systems of coordinates, it is explained that catalogues of stars giving positions with respect to a plane which is independent of the earth's motions would have the great advantage that they would not get out of date as our present catalogues do, as only small corrections for proper motion would be required. The most obvious circle of reference is that provided by the Galaxy, for almost ever) feature either of distribution or of motion of the various classes of stars is based on the Galaxy as a plane of symmetry. It is difficult to give precision to> the definition of the galactic circle, but from a consideration of eight determinations, Dr. Crommelin suggests that the adopted position of the north galactic pole, for the equinox of 1900, should be R.A. 12h. 42m. 37s., decl. +270.32′. It is further suggested that an actual star should be selected to mark the zero of galactic longitude, say a Cygni, which has an extremely small proper motion. The general adoption of some-such scheme has been widely advocated, and will doubtless sooner or later be realised.
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Our Astronomical Column . Nature 100, 473–474 (1918). https://doi.org/10.1038/100473a0
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DOI: https://doi.org/10.1038/100473a0