Abstract
Double Star Measures at Johannesburg.—Circular No. 80 of the Union Observatory is wholly occupied with double star measures made by Mr. W. H. van,den Bos. There are 1393 measures of 604 pairs; the 9-inch refractor is used for such pairs as are within its reach; the 261/2-inch for more difficult ones. Some pairs within reach of northern observers are measured for a check on personality in measuring. One of these is Sirius; there are five measures of the prin cipal pair AB, which agree closely with the ephemeris from Aitken's orbit; two measures of the suspected third companion C, date 1929–213, give P.A. from B 132.6°, distance 1.54″; the note on one night is “C sharp and stellar regarded as quite certain, good measure”; but a later note states that the real existence of C is still regarded as doubtful. A bar across the object glass was found to aid observation in this case; there were dark lanes between the diffracted patches of light; a faint object in these lanes was more easily seen; it is suggested that the device might be useful for Procyon. Three com panions of Nova Pictoris were measured; position angles, 70°, 230°, 10°; distances, 0.5″, 0.6″, 0.3″; dates not given. An interesting new close pair is v Indi; magnitudes, 6.1, 6.2; P.A. 0°, distance 0.14″. As this star has a parallax of 0.034′ (Voute), it is likely to show orbital motion. With the circular are issued twelve more sheets of the photographic star-atlas of the southern heavens that is being made with the Franklin Adams camera; they are ruled with the lines of R.A. and Decl. for the equinox of 1875.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column. Nature 125, 684 (1930). https://doi.org/10.1038/125684a0
Issue Date:
DOI: https://doi.org/10.1038/125684a0