NGC 6520 and B86 - Part of the Large Sagittarius Star Cloud

NGC 6520, B86

The photograph shows the northwestern part of the Large Sagittarius Star Cloud, which is the densest star cloud of the entire Milky Way. Although it lies in the direction of the center of the galaxy, it is in fact located in the nearby spiral arm called the Sagittarius arm and not in the galactic hub. The western edge of the cloud is limited and obscured by interstellar dust clouds. There is perhaps ten times more dark matter in the Milky Way then is contained in stars or glowing nebular material. The center of the galaxy is obscured by as much as 30 magnitudes of absorbing material!

Barnard 86 is a black spot in the Large Sagittarius Star Cloud spanning 4.5' x 3' which is charmingly placed next to the small open cluster NGC 6520, together they make a nice contrast. B86 is just a little smaller than the cluster and is essentially a dust cloud absorbing the starlight from behind it. NGC 6520 has an apparent size of 5 arcminutes and contains 25 stars from magnitudes 9 down to 12.

The Large Sagittarius Star Cloud is bright to the naked eye and increases in brightness the further south the observer is located.

Great Sagittarius Starcloud - telelens photograph.

Exposure Data

Instrument: TMB 4.1" f/6.2 APO
F/stop: 6.2
Exposure: 43 minutes
Film: Kodak Ektachrome E200
Exposure start: 01:25 MESZ
Date: July 6, 2002
Location: Ebenwaldhöhe, Lower Austria
Conditions: Visual limiting magnitude 5.5 mag, seeing 5, temperature 12°C, no wind, low humidity
Autoguider: Meade Pictor 216 XT, max. error: 2
Enhancement: Adobe Photoshop 6.0
Notes: Low altitude of photographed field.

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