Baade's Window with the two globular clusters NGC 6522 (right) and NGC 6528, photographed with the 3.9-meter Anglo-Australian Telescope. Credit: David Malin.
Baade's window is a small clearing in the dust clouds of Sagittarius, near the globular cluster NGC 6522, through which astronomers can view stars in the galactic bulge. The window lies 3.9 degrees south of the galactic center, corresponding to a line of sight that passes within 1,800 light-years of the Milky Way's heart. It is named after Walter Baade who used it to observe RR Lyrae variables in the bulge region.