Hans Schjellerup

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Hans Carl Frederik Christian Schjellerup (born February 8, 1827 in Odense , † November 13, 1887 in Copenhagen ) was a Danish astronomer .

Life

After finishing school, Schjellerup was apprenticed to a watchmaker. However, it did not correspond to his scientific inclinations, so that he continued his own studies and in 1848 passed the entrance examination at the Polytechnic School in Copenhagen . After only two years he was able to finish his studies in 1850 with the final exam in applied mathematics and mechanics. In 1851 he took up a position as an observer at the old university observatory. A few years later he also became a teacher of mathematics and astronomy at the Naval Officers School and a drawing teacher at the Polytechnic School. He held this post until his death.

The old observatory was built under Longomontanus as a tower in the city center a good 200 years earlier . Despite being repeatedly equipped with new instruments, it was meanwhile only partially suitable for astronomical work because of its cramped space, which did not allow for permanently installed instruments, and because of its unfavorable city location. Schjellerup's observation work therefore had to be limited to temporary work . He therefore devoted himself more to theoretical investigations such as calculating the orbit of minor planets and comets, including in particular the comet of 1580 based on the original observations of Tycho Brahe .

When the chair of astronomy at the university became vacant in 1855, Schjellerup did not receive this post because he was not a graduate of the university. When the construction of a new observatory was considered, Heinrich Louis d'Arrest was preferred to him for the post of director, as he had already made a name for himself in astronomy. The new university observatory , completed in 1861, offered Schjellerup much better conditions for astronomical observations. In 1875, after d'Arrest's death, he was offered the professorship of astronomy. However, he declined, partly because of the financial losses involved, partly because he had lost the leisure time for his own studies, which the routine work at the observatory and other obligations left him with.

astronomy

The new observatory was a ten imperial en refractor by Merz and a meridian circle by Pistor & Martins equipped. With this meridian circle, Schjellerup began in September 1861 to observe stars - mainly eighth and ninth magnitude - in the zone between + 15 ° and −15 ° declination . As early as 1864 he was able to submit a catalog to the Royal Danish Academy of Sciences with the mean locations of 10,000 stars calculated for 1865 .

In 1866 Schjellerup published a catalog of red stars, which were of particular interest for the then newly introduced spectroscopy as the supposed final stages of stellar evolution.

Schjellerup started learning oriental languages, mainly Arabic and Chinese. In the Danish Royal Library he found a manuscript by the Persian astronomer al-Sufi , in which the latter gave a careful description of the fixed stars based on his own observations. These observations came from the 10th century, so they were roughly in the middle between the Almagest and modern star catalogs. Since no other observations of star brightness from that epoch are known, Schjellerup translated this work (with reference to a second manuscript from St. Petersburg) and made the brightness observations accessible to astronomical research. However, in view of the difficulties he had faced in the publication of the Étoiles Fixes , he gave up his plan to develop other ancient observations through translations in another work . Instead, he began in 1881 with a series of individual publications under the title “Recherches sur l'Astronomie des Anciens” ( Investigations into the astronomy of the ancients ), of which only three had appeared before his death. The first dealt with the method used in Alexandria to measure time at night using star culminations; the second examined Chinese observations of solar eclipses; the third compared seven conjunctions reported by Ptolemy between the moon and fixed stars with modern lunar tables .

The Schjellerup lunar crater is named after him.

Works (selection)

  • Stjernefortegnelse indeholdende 10000 Positioner af teleskopiske Fixstjerner imellem - 15 og + 15 Graders declination. Copenhagen 1864 ( digitized )
  • Description of the Étoiles Fixes, composée au milieu du dixième siècle de notre ère par l'Astronome Persan Abd-al-Rahman al-Sûfi. St. Petersburg 1874 ( digitized version )

literature

Web links

Individual evidence

  1. ↑ HCFC Schjellerup: A Uranometrie from the tenth century. Astronomische Nachrichten, Vol. 74 (1869), p. 97 ( online )
personal data
SURNAME Schjellerup, Hans
ALTERNATIVE NAMES Schjellerup, Hans Carl Frederik Christian
BRIEF DESCRIPTION Danish astronomer
DATE OF BIRTH February 8, 1827
PLACE OF BIRTH Odense
DATE OF DEATH November 13, 1887
Place of death Copenhagen