The development of astrometry and Brorfelde Observatory

Abstract

In a personal and professionally rich narrative, Erik Høg recounts his lifelong work in astrometry – from Brorfelde to the Gaia satellite. The article is an exceptional documentation of how Danish astronomy helped revolutionize the measurement of stars' positions, movements, and distances. The reader is guided through the development of meridian circles, from manual measurements to automated systems and photon counting, with a particular focus on the innovations at Brorfelde. We hear about the collaboration with Peter Naur, the expedition to Australia with the meridian circle from Hamburg-Bergedorf, and how Høg’s ideas about photon-based astrometry led to ESA’s Hipparcos and Gaia. The article concludes with the vision of GaiaNIR – a future successor with infrared sensitivity. This is not just a historical overview, but a deep insight into how precision and technology have driven astronomy into the modern era.