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Coal Sack: Every observer viewing the Southern Cross in a dark night sees very close to the Cross a huge Dark Nebula, like a tremendous hole in the sky. Due to its shape and absence of stars in visual observation it is called the Coalsack.

The image displays this large Dark Nebula in its full extent and demonstrates that there are nevertheless structures present, which only come out with longer photographic exposures.
The two bright stars are the triple star system Acrux, the brightest star of the Cross, at the top and Becrux the second brightest to the left. The bright Open Cluster close to Becrux is the Jewel Box, one of the numerous magnificent clusters in this region of the sky.

Object Coal Sack
Category Nebulae
Designation Coal Sack
Constellation Crux
Optics Canon EF lens 200mm 1:2.8 @ f/3.5
Mount Astro-Physics 900 GTO
Camera SBIG STL 11000M with internal CFW 5
Exposure 6 x 5min each Astrodon RGB filterset. Maxim DL for image acquisition
Calibration Dark + Flat Frame
Guiding Meade DSI Pro II and Skywatcher ED80 as Guide Scope, Maxim DL as guiding software
Processing Maxim DL5,Photoshop. Color Code R,G,B
Location-Date Somerset West, South Africa - 7 Mar 2010
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