Astrometry during the past 2000 years
  The satellite missions Hipparcos and Gaia by the European Space Agency will
together bring a decrease of astrometric errors by a factor 10000, four orders
of magnitude, more than was achieved during the preceding 500 years. This
modern development of astrometry was at first obtained by photoelectric
astrometry. An experiment with this technique in 1925 led to the Hipparcos
satellite mission in the years 1989-93 as described in the following reports
Nos. 1 and 10. The report No. 11 is about the subsequent period of space
astrometry with CCDs in a scanning satellite. This period began in 1992 with my
proposal of a mission called Roemer, which led to the Gaia mission due for
launch in 2013. My contributions to the history of astrometry and optics are
based on 50 years of work in the field of astrometry but the reports cover
spans of time within the past 2000 years, e.g., 400 years of astrometry, 650
years of optics, and the "miraculous" approval of the Hipparcos satellite
mission during a few months of 1980.
