2.4

Using the Carte du Ciel for the extension of the Hipparcos system

Alain Fresneau, Strasbourg

Abstract

The Carte du Ciel ('Die Himmelskarte') was the very first sky survey devoted to provide star maps directly from photographic plates and not by plotting the celestial coordinates of stars observed by transit instruments. This survey got started by 1887.

The goal was to detect all stars down to apparent magnitude 14.5, visible through large refractors. An intermediate photographic survey was achieved in order to fill the gap between transit instrument observations down to apparent magnitude 8 and the 'astrographic catalog' was completed during the first quarter of the 20th century.

A set of 4.5 millions stars down to apparent magnitude 11.5 is presently available in the Hipparcos system and is used as first Epoch positions for stars observed by TYCHO.

The Carte du Ciel plates, combined with modern Epoch photographic surveys, can provide centennial proper motion at an accuracy of 0.2 arcsec and a radiometric calibration at an 0.2 magnitude level.

Bibliographical details:

Alain Fresneau: Using the Carte du Ciel for the extension of the Hipparcos system. In: Peter Brosche, Wolfgang R. Dick, Oliver Schwarz, Roland Wielen (Eds.): The Message of the Angles - Astrometry from 1798 to 1998. Proceedings of the International Spring Meeting of the Astronomische Gesellschaft, Gotha, May 11-15, 1998. (Acta Historica Astronomiae ; 3). Thun ; Frankfurt am Main : Deutsch, 1998, p. 133-140.