Abstract
PHOTOGRAPHIC DETERMINATIONS OF STELLAR POSITIONS.—Dr. B. A. Gould, in a paper presented at the Buffalo meeting of the American Association for the Advancement of Science on August 20, 1886, gives some interesting particulars with regard to his photographic work at Cordova. He states that no northern stars were photographed there except the Pleiades and the Præsepe. On the Pleiades plates all but one of Bessel's stars are found, which fall within the limits of the field; the missing one being of the magnitude 9½, whilst there are depicted on the plates other stars of the magnitudes 10, 10½, and 11. About seventy southern clusters have been repeatedly photographed at Cordova, also more than a hundred double stars, whilst the total number of photographs which Dr. Gould has on hand for measurement is about 1300, only a few having been preserved in which the images are not circular. In addition to these classes of objects, special attention was given for many years to taking frequent impressions, at the proper seasons, of four stars selected, on account of their large proper motions, as likely to manifest appreciable annual parallax. All but one of these four stars—β Hydri—have been included in the lists observed and discussed by Drs. Gill and Elkin at the Cape. Still, it will be a matter of much interest to apply the photographic method of investigation to the same problem, even if for no other purpose than a comparison of the results of the two methods. With regard to the progress made in the measurement of the Cordova photographs, Dr. Gould states that the measurements thus far completed are those of the double stars, the four stars with large proper motion, the Pleiades, the Præsepe, and the clusters Lacaille 4375 and κ Crucis. The corresponding computations have been made as yet only for a portion of the Pleiades plates, but it is expected that all these will be completed at a comparatively early date. The results deduced from the Pleiades photographs will be looked for with much interest, especially as Dr. Elkin has recently executed at Yale College a heliometric triangulation of the principal stars of the group, and the comparison of the results will be a severe test of the photographic method for the determination of stellar positions. But astronomers expect good work from Dr. Gould, and they are not likely to be disappointed. Dr. Gould's paper is published in the Scientific American Supplement, No. 556.
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Our Astronomical Column . Nature 34, 502 (1886). https://doi.org/10.1038/034502a0
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DOI: https://doi.org/10.1038/034502a0