AAO image reference AAT 93. « Previous || Next »
Top left is NE. Image width is about 24 arc min
Image and text © 1993-2002, Anglo-Australian Observatory, photograph by David Malin.
Around the nucleus of the Milky Way swirl vast numbers of relatively faint, old, yellow stars. They are seen overhead on southern winter nights as the brightest part of the Milky Way, the star clouds of Sagittarius. The Galactic centre is itself obscured by dust clouds at visible wavelengths, but in the 1940s, Walter Baade, working at Mt Wilson in the USA, identified a region with a line of sight close to the Galactic centre. This direction has the minimum of obscuration and it was here, in the 'window' around the globular cluster NGC 6522 that he was able to determine the first reliable distance to the centre of the Galaxy. Modern measurements place it at about 25,000 light years away, slightly greater than Baade's result.
Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988:
NGC 6522 Gb 18 03.6 -30 02 s Sgr5.68.6 glob. cl. , B, pL, R, gvmbM, rrr, st 16Related Images
AAT 93a. Baade's Window, around NGC 6522 (wide field)
UKS 20. Clouds of stars and dust in Sagittarius
UKS 21. NGC 6522, gamma Sagittarii and Baade's Window
For details of photographic exposure, search technical table by AAT reference number.
Image availability: Slide