Baade's Window

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title: "Baade's Window" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["milky-way", "galactic-center"] description: "Gap in interstellar dust allowing for observation of the center of the Milky Way Galaxy" topic_path: "general/milky-way" source: "https://en.wikipedia.org/wiki/Baade's_Window" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Gap in interstellar dust allowing for observation of the center of the Milky Way Galaxy ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/6/61/HST_SWEEPS_Galaxy_Location-2006.jpg" caption="Baade's Window on the Milky Way"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/c/c0/Baade's_Window_(Shaded).jpg" caption="Near-Center of the Milky Way with Baade's Window shaded."] ::

Baade's Window is an area of the sky with relatively low amounts of interstellar dust along the line of sight from Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. This makes the apparent Large Sagittarius Star Cloud visible.

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. It is centered at a galactic longitude (l) of 1.02° and a galactic latitude (b) of -3.92°, which corresponds to a right ascension of 18h 03m 32.14s and a declination of -30d 02m 06.96s, in the direction of the constellation Sagittarius.

History

Walter Baade observed the stars in this area in the mid-1940s using the 100 in 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.{{cite journal | title = A Search For the Nucleus of Our Galaxy | author = Baade, W. | journal = Publications of the Astronomical Society of the Pacific | volume = 58 | issue = 343 | pages = 249–252 |date=August 1946 | bibcode = 1946PASP...58..249B | doi = 10.1086/125835}}

In 2006, the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) conducted an astronomical survey to monitor 180,000 stars for seven days to detect extrasolar planets via the transit method. | url=http://cdsweb.u-strasbg.fr/cgi-bin/Dic-Simbad?SWEEPS | title=SIMBAD Details on Acronym: SWEEPS | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | access-date=2009-05-21

Significance

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b1/N6522_32ins.jpg" caption="[[NGC 6522]] (upper right) and [[NGC 6528]] (lower left) are visible within Baade's Window."] ::

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". 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.{{cite journal | title = Extinction Map of Baade's Window | author = Stanek, K.Z. | journal = Astrophysical Journal Letters | volume = 381 | issue = 1 | pages = 219–226 | year = 1996 | bibcode = 1996ApJ...460L..37S | doi = 10.1086/309976|arxiv = astro-ph/9512137 | s2cid = 11590782

Baade's Window is the largest of the six areas through which central bulge stars are visible.{{cite journal |title=Low-extinction windows in the inner Galactic Bulge |author1=Dutra C.M. |author2=Santiago B.X. |author3=Bica E. |journal=Astronomy & Astrophysics |volume=460 |issue=1 |pages=L37 |year=2002 |doi=10.1051/0004-6361:20011541 |bibcode=2002A&A...381..219D |arxiv=astro-ph/0110658 |s2cid=15619180

OGLE and other observation programs have successfully detected extrasolar planets orbiting around central bulge stars in this area by the gravitational microlensing method.

Stars observed in Baade's Window can be called BW stars, similarly giant stars can be called BW giants.

References

References

1. (May 2011). "Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window". [[Astronomy & Astrophysics]].
2. "NAME Baade Window".
3. "Your NED Search Results-Input: Galactic/Output: Equatorial J2000.0".
4. Rich, R. M.. (March 1988). "Spectroscopy and abundances of 88 K giants in Baade's Window". Astronomical Journal.

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