Abstract
DETECTION OF NEW NEBULÆ BY PHOTOGRAPHY.—Prof. Pickering gives a brief account, in No. 6 of the Annals of Harvard College Observatory, vol. xviii., of some experiments he has recently conducted as to the advantages of a photographic doublet over an ordinary astronomical object-glass for astronomical work, and especially in photographing nebulæ. A number of plates were exposed upon the region of Orion, the instrument used being the Bache telescope, which has a photographic doublet with an aperture of 8 inches and a focal length of 44 inches; each plate covered a region 10° square, the definition being good within 31/2° of the centre of the plate. The result of the experiments was the detection of twelve new nebulæ; fourteen nebulæ were seen on the photographs that were also given in Dreyer's Catalogue, and four nebulæ in the Catalogue were not represented on the plates. A similar proportion of discovery over the entire sky would mean some 4000 or 5000 new nebulæ, and 400 plates would be sufficient for a complete survey, provided here was no overlapping, and no plates proved defective.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column . Nature 39, 232 (1889). https://doi.org/10.1038/039232a0
Issue Date:
DOI: https://doi.org/10.1038/039232a0