Affiliation: | (1) The Astronomical Institute, Utrecht;(2) Royal Aircraft Establishment, Farnborough, England;(3) Astronomical Institute, Space Research Laboratory, Utrecht;(4) Observatoire de Paris, Section d'astrophysique, Meudon, France;(5) ESTEC, Noordwijk;(6) Stockholm-Observatory, Sweden;(7) Thiokol, Chemical Corporation, Bristol, Penn., U.S.A.;(8) The Astronomical Institute, Utrecht |