As in the case of our FK6,
(using ground based data provided by the FK5 to improve Hipparcos' results),
we also used the
(TYC2) to increase the number of stars
with such better data: The combination of HIPPARCOS and TYC2 data gives
improved results for 89 908 stars.
This number of objects could be treated as single stars.
The catalogue gives proper motions
with a typical mean error of 0.83 mas/year (about a factor of
1.3 better than Hipparcos for this sample of stars).