Number of Hipparcos observations

Hipparcos observed more than 100000 stars during its 3-year observing programme, and has produced positional data for these stars 100 times more precise than could be obtained from telescopes on the ground. The map is in ecliptic coordinates. (From the Hipparcos and Tycho Catalogues, ESA SP-1200 - volume 1.) [Image Date: 01-04-97] [97.05.003-002]