NGC 6522, gamma Sagittarii and Baade's Window
AAO image reference UKS 21.    « Previous || Next »

NGC 6522, gamma Sagittarii and Baade's Window
Top left is NE. Image width is about 1.5 degrees
Image and text © 1987-2010, Australian Astronomical Observatory
Photograph from UK Schmidt plates by David Malin.


The German-American astronomer Walter Baade selected for study a region of the crowded star fields in Sagittarius where he believed the Galactic dust obscuration was both uniform and minimal. He used this line of sight to establish the distance of the unseen Galactic centre, using variable stars as his yardstick. He found it to be about 30 000 light years away. This part of the sky, around the globular cluster NGC 6522, is now known as Baade's window. The brightest star in the photograph is gamma Sagittarii, a deep yellow, naked eye star of about third magnitude. It is in the foreground at a distance of about 100 light years.

Related images
AAT 22.  Barnard 86 and NGC 6520
AAT 28.  Wide angle view towards the Galactic centre
AAT 92.  Barnard 86 and NGC 6520, wide angle view
AAT 93.  Baade's Window, around NGC 6522
UKS 20. The star clouds of Sagittarius
Constellation of Sagittarius (external site)

For details of object position and photographic exposure, search technical table by UKS reference number.

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Updated by David Malin, 2010, July 25