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Accueil > Séminaires > Archive des séminaires d’Utinam > 2013

Erik Høg

Astrometry Lost and Regained

mercredi 26 juin 2013, 14h

salle de conférences de l’observatoire

Erik Høg, Professeur émérite, Institut Niels Bohr, Copenhague, Danemark

Résumé :

From an experiment in Copenhagen in 1925 to the Hipparcos and Gaia space missions. Astrophysicists need accurate positions, distances and motions of stars in order to understand the evolution of stars and the universe. Astrometry provides such information, but this old branch of astronomy seemed dull and old fashioned to most astronomers in the competition with astrophysics. In fact, astrometry was facing extinction during much of the 20th century. The direction to go was shown by observations at the Copenhagen Observatory in 1925 with a new technique : photoelectric astrometry. Digital techniques were successfully introduced in photoelectric astrometry with an astrometric telescope at the Hamburg Observatory in the 1960s. This development paved the way for space technology as pioneered in France and implemented in the European satellite Hipparcos, launched in 1989. The new ESA satellite Gaia, a million times more powerful than Hipparcos is due for launch in 2013. Subject of the talk is this history of 100 years astrometry in which the speaker has been involved since 1954.

Curriculum vitae :

Erik Høg - Associate Professor, Emeritus, astronomer, dr. scient., Niels Bohr Institute, Copenhagen.
Website :
Member of the Hipparcos and Gaia Science Teams from 1975 to 2007. Proposed in 1975 a new design of a scanning astrometric mission which became Hipparcos. Proposed in 1992 an astrometric mission with CCDs in time delayed integration which became Gaia. Published in 2000 by Høg et al. : "The Tycho-2 Catalogue of the 2.5 million brightest stars."
Received in 1999 the ESA Director of Science medal for "outstanding contribution to the science program."
The International Astronomical Union gave the name Erikhøg to an asteroid. It has a diameter of 22 km and a mass of 13 million billion kg.
The Struve Medal from Russia awarded in 2009 :

Nouvel article :
Astrometry 1960-80 : from Hamburg to Hipparcos :