Abstract
DOUBLE STAR OBSERVATIONS.—In Ast. Nach., No. 3370, Dr. Doberck, while discussing the elements of η Corona; Borealis, takes the opportunity to determine the probable error that accompanies the observation of position angle and distance in the case of the better-known double star observers. Three stars have been selected for the discussion. η Coronæ, a close double, in which the probable errors are referred to a common distance of 0″˙7 a Centauri, reduced to a mean distance of 10″, and, of course, including a different class of observers; and γ Virginis, with a mean distance of 2″˙5. Dr. Doberck might with advantage have given the aperture of the telescope with which the observations have been made, but a glance at the list is sufficient to show that the greatest accuracy, as might have been anticipated, is on the side of the large telescopes. In the case of η Coronæ, Profs. Hall and Burnham are the only observers whose probable errors fall below 1° in position angle. In distance, their only competitor is M. Perrotin, who also has the advantage of large aperture. With γ Virginis, where the components are more widely separated, telescopes of moderate size are able to compete advantageously, and the measures of MM. Duner and Schiaparelli appear quite as trustworthy as those of Prof. Hall. The probable errors attached to observations made in the southern hemisphere are, on the whole, slightly larger than those derived from northern observers.
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Our Astronomical Column. Nature 54, 426–427 (1896). https://doi.org/10.1038/054426a0
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DOI: https://doi.org/10.1038/054426a0