Carte du Ciel

from Wikipedia, the free encyclopedia

The Carte du Ciel (French sky map ) was a never completed international project to measure the positions of about one million stars up to the 11th magnitude and to create a photographic sky map up to the 14th magnitude.

Participating observatories
Observatory declination
From To
Greenwich + 90 ° + 65 °
Rome + 64 ° + 55 °
Catania + 54 ° + 47 °
Helsinki + 46 ° + 40 °
Potsdam + 39 ° + 32 °
Oxford + 31 ° + 25 °
Paris + 24 ° + 18 °
Bordeaux + 17 ° + 11 °
Toulouse + 10 ° + 5 °
Algiers + 4 ° −2 °
San Fernando −3 ° −9 °
Tacubaya −10 ° −16 °
Santiago −17 ° −23 °
La Plata −24 ° −31 °
Rio −32 ° −40 °
Cape Town −41 ° −51 °
Sydney −52 ° −64 °
Melbourne −65 ° −90 °

The project was initiated in 1887 by the Paris Observatory under its director Ernest Mouchez , who had recognized the possibilities of photography for mapping the stars (photographic astrometry ). He developed a project in which the entire sky should be covered with 22,000 photo plates, each 2 ° × 2 ° in size. He managed to enlist the help of numerous observatories around the world, each of which was assigned a part of the sky for observation.

In a first step, the exact positions of a few thousand reference stars in different parts of the sky were determined by using meridian circles to determine their declination and transit time through the meridian . Afterwards, photographic images of the sky were obtained and the celestial coordinates ( right ascension and declination ) of many stars were determined in laborious manual and arithmetic work in comparison to the reference stars. Semi-skilled workers, mainly women, were employed in large numbers for this purpose.

Results

After decades of work, the project was replaced by more modern techniques and was never fully completed, although a star catalog was published in 1958 . The effort required had been underestimated, so that the originally assumed duration of 10 to 15 years could not be adhered to.

Although a few double stars and stars with high proper motion were discovered, the success remained low compared to the enormous amount of time and effort involved. In addition, the participating astronomers remained busy with a project, especially in France, that required constant, little creative work, while in other places the development of astronomy from astrometry to modern astrophysics began.

Individual evidence

  1. ^ A b History of the Carte du Ciel and Astrographic Catalog. In: Astrographic Catalog Publications and References. US Naval Observatory and Copenhagen University Observatory, accessed July 8, 2019 .
  2. ^ A b Derek Jones, FRAS: The scientific value of the Carte du Ciel . In: Astronomy & Geophysics, Volume 41, Issue 5, October 2000, Pages 5.16–5.20 . October 1, 2000. doi : 10.1046 / j.1468-4004.2000.41516.x .
  3. ^ The Astrographic Catalog: A Century of Work Pays Off. In: Sky & Telescope , Volume 95, Issue 6, pp. 40-44 ,. Sky Publishing Corporation, accessed July 8, 2019 .