Système de référence stellaire : effets systématiques Stellar reference system: Systematic effects

Instituto Astronômico e Geofísico-Universidade de São Paulo, Caixa Postal 9638, 01065-970, São Paulo-SP, Brésil

Send offprint request to: V.A.F. Martin

Received: 10 January 1996
Accepted: 7 February 1996

Abstract

We discuss two different ways to determine the systematic effects on the star's observations obtained with the astrolabe. The first one is related to the absolute determination of the declinations got through stars belonging simultaneously to and zenith distance programmes. The absolute declinations were obtained from a global reduction including all the data. The second way uses a sum of chosen functions, added to the observational results in zenith distance obtained with astrolabes, which represent both the systematic differences and between catalogues of stars and the instrumental effects Δ I. With this method it is possible to associate several different catalogues as only one. The interest is that it allows the utilization of even single passage stars to get systematic differences and , what is not possible in classical procedure of astrolabe data reduction.