The Tycho-2 Catalogue:
Star density


The density of Tycho-2 stars on the sky shown in galactic coordinates (panel a) and in equatorial coordinates (panel b). Some of the dark features reveal low star density due to nearby Galactic dust clouds, while other reveal variations in the limiting magnitude caused by the scanning pattern of the satellite. The densest areas have more than 350 stars deg-2, while the thinnest have close to zero. The average density varies from 25 stars deg-2 at b=±90o and 50 stars deg-2 at b=±30o to 150 stars deg-2 at b=0o.