AbstractA new optical realization of the ICRS is built upon the data of the Hipparcos catalog and 60 observational and compiled astrometric ground-based catalogs of the 20th century reduced to the Hipparcos system. It is in print as two catalogs. The ‘Proper Motions of Fundamental Stars’ catalog (PMFS) contains proper motions of 4638 stars common to the Hipparcos and Basic FK5/FK5 Extension improved to the level of 0.5 mas. 1800 of the stars are the photocenters of stellar systems unresolved in the astrometric observations. The duplicity parameters of those systems were collected in the ‘Astrometric Binaries’ catalog (ABC). The photocenter nonlinear motions of several hundred of those astrometric binaries were detected and separated from their proper motions. The periods and amplitudes of several astrometric binaries are discussed in detail. This research will be continued for all Hipparcos stars observed from the ground in the 20th century. The web site is http://www.geocities.com/georgegontcharov/
A SCHEME FOR OPTICAL REALIZATION OF WALSH TRANSFORMATION