The Tycho catalog (TYC), later called Tycho 1 catalog (TYC1), contains the results of an astronomical survey of the starry sky, which the astrometric satellite Hipparcos carried out from 1989 to 1993.
The publication of the Hipparcos measurement results in 1997 brought astrometry a leap forward:
Hipparcos was able to measure the star locations , parallaxes and proper motions of 118,000 stars with a previously unattainable precision of about 0.003 "/ semester or 0.002" / semester; these data form the Hipparcos catalog . In addition, a second instrument on board measured 1,058,332 stars with an accuracy of ± 0.02 "; this data forms the Tycho catalog. This is 20 to 50 times more accurate and four times the number of stars than the previous one the usual star catalogs .
In 2000 the Tycho 2 catalog (TYC2) was published with a total of 2,539,913 of the brightest stars, that is 99% of the stars up to a magnitude of 11. It is based on the same data as the Tycho catalog.
The contents of the Tycho catalog are freely accessible. They allow anyone celestial objects with telescope and CCD - camera accurately and semi-automatically calibrate.