Abstract
ON THE PARALLAX OF THE PLANETARY NEBULA B.D. +41°.4004.—During the summer of 1892 Dr. J. Wilsing began a series of photographs of Webb's planetary nebular B.D. +41°˙4004, using the new photographic refractor of the Potsdam Observatory, with the intention of determining the parallax. In the current number of Astronomische Nachrichten (No. 3190) he gives an account of the measurements made. The undertaking seems to have been especially difficult on account of the numerous errors that were liable to arise, and also to the lack of sharpness of the image of the nebula on the photographic plate. From June 1892 to June 1893 he obtained thirty-four plates with two exposures on each of eight minutes duration, and they were all measured with the Repsold's measuring apparatus, a description of which instrument is given in vol. v. of the Publications of the Potsdam Astrophysical Observatory. Six stars were used for comparison, and the distance of the nebula was measured from two of these start, the others being used for finding the value in seconds of arc of the measured distances, &c. The distances measured show a distinct decrease, as will be gathered from the following table, when N. 3 and N. 6 denotes the distances from the two companion stars respectively:—
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column. Nature 48, 548 (1893). https://doi.org/10.1038/048548a0
Issue Date:
DOI: https://doi.org/10.1038/048548a0