SCHJELLERUP, HANS CARL FREDERIK CHRISTIAN

(b. Odense, Denmark, 8 February 1827: d. Copenhagen, Denmark, 13 November 1887)

astronomy.

Schjellerup was trained as a watchmaker, but through the interest and help of H.C. Oersted he was admitted to the Polytechnic School of Copengagen, where he passed the final examination in applied mathematics and mechanics. in 1851 he was appointed senior astronomer at the Copenhagem gen observatory, a post he held until his death. In 1857 he received the doctorate at Jena with a dissertation deriving the orbit of the comet of 1580 by means of Tycho Brahe’s observations.

In 1861–1863 Schjellerup observed 10,000 positions of faint stars in declinations between —15° and +15° using the new Pistor-Martin meridian circle. A catalog, inspired by Bessel’s zone observing about forty years earlier, was published in 1864 by the Royal Danish Academy. Schjellerup’s catalog. outstanding at the time for its completeness and accuracy. was used as recently as 1952 for determining the constant of precession.

Schjellerup compiled two catalogs of colored stars (1866. 1874); the second, an extension of the first. contains 400 stars. During the same period several astronomers started a survey of the spectra of such stars. and Schjellerup’s compilations appeared in time to be used in this work.

Schjellerup also made a signal contribution to the history of astronomy. At an advanced age he studied oriental languages, especially Arabic and Chinese. He had access to a pair of Arabic manuscripts, one in the Royal Library at Copenhagen and the other in the Imperial Library at St. Petersburg, which contain a description of the sky elaborated about 950 by the Persian astronomer al’Süfi. Al’Süfi had made a careful comparison between Ptolemy’s catalog from about A.D. 150. which contains the positions and magnitudes of about 1,000 stars. and the sky itself: his specifications of relative magnitudes are the only series of this kind of observation that remains from the years between antiquity and modern times. Schjellerup’s French translation was published in 1874 by the Academy of St. Petersburg.

Another result of his rare combination of linguistic and scientific ability was Schjellerup’s control of different moon tables of his time. taking into account three solar eclipses from 708, 600, and 548 B.C. that he found mentioned in ancient Chinese literature.

BIBLIOGRAPHY

I. Original Works. Schjellerup’s writings include “Tycho Brahes Original- Observationer, benyttede til Banebestemmelse af Cometen 1580”, in Kongelige Danske Videnskabernes Seldkabs Skrifter. Naturv’math. Afd., 5th ser.,4 (1856), 1–39; Stjernefortegnelse indeholdende 10000 Positioner af teleskopiske Fixstjerner imellem —15 og +15 Graders Deklination (Copenhagen, 1864): “Catalog der rothen, isolirten Sterne. welche bis zum Jahre 1866 bekannt geworden sind”, in Astronomische Nachrichten, 67 (1866). 97 –112: “Eine Uranometrie aus dem zehnten Jahrhundert” ibid., 74 (1869), 97–104: “Bidrag till Bedømmelsen af de moderne Maaneelementers Paalidelighed”, in Oversigt over det K. Danske Videnskabernes Selskabs Forhand linger (1874), 64–95: Description des éoiles fixes composeés au milieu du dixiè me siècle de notre ère par l’ astronome persan Abd-al-Rahman al’Süfi (St. Petersburg, 1874): “Zweiter Catalog der rothen, isolierten Sterne. Vervollständigt und fortgeführt bis zum Schluss des Jahres 1874” in Vierteljahrsschrift der Astronomischen Gesellschaft, 9 (1874), 252–287: and “pRecherches sur l’astronomie des anciens”, in Copernicus (Dublin), 1 (1881), 25–39, 41–47, 223–236.

II. Secondary Literature. Obituaries are J. L. E. Dreyer, in Monthly Notices of the Royal Astronomical Society, 48 (1888), 171–174; V. Hjort, in Tidsskrift for Mathematik, 5th ser., 5 (1887), 148–153; and J. Holetschek, in Deutsche Rundschau für Geographie, 10 (1888), 381–382; and in Sirius, 21 (1888), 161–163. See also J. E. Gordon, “Derivation of the Constant of Precession From a Comparison of the Catalogues of Schjellerup (1865.0) and Morin-Kondratiev (1900.0)”, in Izvestiya Glavnoi astronomicheskoi observatorii v Pulkove, 19 . pt. 1(1952), 72–121.

Axel V. Nielsen