The Hipparcos Catalogue is a catalogue of 118,218 stars, mostly down to magnitude 8 but with a sampling of dimmer ones (chosen for their unusual or interesting properties), surveyed by the Hipparcos satellite and published in 1997. It contains the most precise measurements of positions, parallaxes, proper motions, and magnitudes ever made; although for stars dimmer than the ones surveyed, other catalogues must still be used. The accurate parallaxes have led to a vastly improved knowledge of the distances of stars out to a few hundred light-years from the Sun. Magnitudes given by the Hipparcos dataset were measured using a device sensitive to a wide range of wavelengths (mostly visual). These magnitudes are unique to the detector on the satellite; they correspond roughly, but not exactly, to visual magnitudes, and are called Hipparcos magnitudes.