E. Tengstrom G. Teleki The IAU symposium no 89, 'Refractional Influences in Astrometry and Geo- desy' , was held at the University of Uppsala, Sweden, during August 1 through August 5, 1978. It was a joint meeting of IAU and lAG, cosponsor- ed by lAG and IUGG. Considerable financial support was also given by the Swedish Natural Science Research Council, the Wallenberg Foundation in Stockholm and the University of Uppsala. The Scientific Organizing Committee included G. Teleki (chairman), W. Altenhoff (Bonn), P. Bender (Boulder), L. Hradilek (Prague), J.A. Hughes (Washington D.C.), J. Kakkuri (Helsinki), A.J. Nefedieva (Kazan), J. Saastamoinen (Ottawa), C. Sugawa (Mizusawa) and E. Tengstrom (Uppsala). The Local Organizing Committee included E. Tengstrom (chairman and con- venor), I. Ohlsson (adm. secretary and treasurer), P. Hodacs, S-G. Martensson, S. Eklund and M. O'Shaughnessy, all from Up~sala. This symposium was the first international meeting of astronomers and geodesists connected with refraction phenomena. The proceedings of this symposium contain all papers accepted by its Scientific Organizing Committee, and all discussions around them to- gether with all contributions during special workshops and round-table discussion programs.

E. Tengstrom G. Teleki The IAU symposium no 89, 'Refractional Influences in Astrometry and Geo- desy' , was held at the University of Uppsala, Sweden, during August 1 through August 5, 1978. It was a joint meeting of IAU and lAG, cosponsor- ed by lAG and IUGG. Considerable financial support was also given by the Swedish Natural Science Research Council, the Wallenberg Foundation in Stockholm and the University of Uppsala. The Scientific Organizing Committee included G. Teleki (chairman), W. Altenhoff (Bonn), P. Bender (Boulder), L. Hradilek (Prague), J.A. Hughes (Washington D.C.), J. Kakkuri (Helsinki), A.J. Nefedieva (Kazan), J. Saastamoinen (Ottawa), C. Sugawa (Mizusawa) and E. Tengstrom (Uppsala). The Local Organizing Committee included E. Tengstrom (chairman and con- venor), I. Ohlsson (adm. secretary and treasurer), P. Hodacs, S-G. Martensson, S. Eklund and M. O'Shaughnessy, all from Up~sala. This symposium was the first international meeting of astronomers and geodesists connected with refraction phenomena. The proceedings of this symposium contain all papers accepted by its Scientific Organizing Committee, and all discussions around them to- gether with all contributions during special workshops and round-table discussion programs.