Non-tidal vertical variations and the past star catalogs

Tidal vertical variations have been removed in astrometric observations, but the non-tidal ones remain unknown. From the repeated observations of gravimetric networks in China, the non-tidal vertical variations at Beijing-Tangshan and West Yunnan are determined, which are of the order of 0.″2. Astrometric results, including past star catalogs, based on these observations should be corrected.