 Around 1950, he developed the UVBYß photoelectric system, which is still in use today.In the 1950s, the Østervold Observatory was replaced by the Brorfelde Observatory located near the town of Holbæk, which was provided with a very fine meridian circle and a Schmidt telescope with a camera that used photographic film.It houses a 300 double reflector with a focal depth of 4.9m.