Baade's Window is an area of the sky with relatively low amounts of interstellar "dust" along the line of sight from the Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. It is named for astronomer Walter Baade who first recognized its significance. This area corresponds to one of the brightest visible patches of the Milky Way.
Walter Baade surveyed the stars in this area in the mid-1940s using the 100-inch (2.5 m) Hooker telescope at Mount Wilson Observatory in California while searching for the center of the Milky Way galaxy. Up until this time the structure and location of the galactic center was not known with certainty.
Baade's Window is frequently used to study distant central bulge stars in visible and near-visible wavelengths of light. Important information on the internal geometry of the Milky Way is still being refined by measurements made through this "window". It is in the direction of the constellation of Sagittarius. The window is now known to be slightly "south" of the main central galaxy bulge. The window is irregular in outline and subtends about 1 degree of the sky. It is centered on the globular cluster NGC 6522.
Baade's Window is the largest of the six areas through which central bulge stars are visible.
Stars observed in Baade's Window can be called BW stars, similarly giant stars can be called BW giants.
- Baade, W. (August 1946). "A Search For the Nucleus of Our Galaxy". Publications of the Astronomical Society of the Pacific. 58 (343): 249–252. Bibcode:1946PASP...58..249B. doi:10.1086/125835.
- "NAME Baade Window". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2011-03-13.
- Stanek, K.Z. (1996). "Extinction Map of Baade's Window". Astrophysical Journal Letters. 381 (1): 219–226. arXiv:astro-ph/9512137. Bibcode:1996ApJ...460L..37S. doi:10.1086/309976.
- Dutra C.M.; Santiago B.X.; Bica E. (2002). "Low-extinction windows in the inner Galactic Bulge". Astronomy & Astrophysics. 460 (1): L37. arXiv:astro-ph/0110658. Bibcode:2002A&A...381..219D. doi:10.1051/0004-6361:20011541. Retrieved 2018-04-12.