Abstract
THE NEUCHÂTEL OBSERVATORY.—Dr. Hirsch, the Director of the Neuchâtel Observatory, has published his Annual Report for the year 1886, dated June 21, 1887. On the whole, Dr. Hirsch reports that, as far as his Observatory is concerned, the year 1886 was somewhat more favourable for astronomical observations than was 1885. In 1886 there were 154 nights on which observations were made, and 124 days on which no observations were possible, the longest interval without observations having been 7 days; whilst in 1885 the number of observing nights was 150, the number of days without observations 135, and the longest interval without observations 20 days. The meridian observations made during the year comprise 192 observations of the sun, 16 of planets, 1401 of fundamental stars, and 909 of stars contained in M. Lœwy's Catalogue of Moon-Culminating and Longitude Stars. The equatorial telescope has been employed in the observation of planets and comets with the ring micrometer, the position micrometer not being available until the small incandescent lamps, which are to be provided for purposes of illumination, have been supplied. Dr. Hirsch gives some interesting particulars with regard to the azimuthal movements of the meridian circle, as well as of the distant marks used for determination of azimuth error. The maximum easterly azimuth (+ 3.03s.) of the meridian circle during the year was observed on March 11, whilst the maximum westerly azimuth (- 1.02s.) was observed on September 1; the total range throughout the year 1886 was therefore 4.05s., the corresponding mean value for 22 years being 5.20s. It appears, however, that the three meridian marks (two to the north and one to the south) do not participate in this movement. The azimuth of one of the north marks, situated at a distance of 100 m. from the Observatory, varied during 1886 between + 0.24s. on May 19 and - 0.25s. on August 29, thus showing a total range of only 0.49S. The other more distant north mark showed a range of 0.42s., the extremes being + 0.18s. on April 16 and - 0.24s. on August 7; whilst the south mark at about 10 km. distance varied from + 0.40s. on May 14 to - 0.01s., on July 3, the range being therefore 0.41s. The marks are consequently well adapted for determining the azimuth of the meridian circle, the mean of the three giving this element, according to Dr. Hirsch's estimation, to ± 0.012s. nearly.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column . Nature 36, 477–478 (1887). https://doi.org/10.1038/036477a0
Issue Date:
DOI: https://doi.org/10.1038/036477a0