M71 - A Globular Cluster |
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M71 (NGC 6838) is a loose, low density, globular cluster found in Sagitta (The Arrow). Some early astronomers incorrectly labled it a dense open cluster. It turns out its fairly close (for a globular) at 13000 light years. It shines at magnitude 8.3, and is 7.2' across.
This shot was taken at f/6.3 with the 12" LX200, AO7, and ST-8E CCD from my home dome in Monmouth Oregon on Sept. 7, 2001.
Filter | Exposure | Count | Binning |
Luminance | 38 min | (sum of RGB data) | |
Red | 10 min | 5 x 2 min | 1x1 |
Green | 10 min | 5 x 2 min | 1x1 |
Blue | 18 min | 9 x 2 min | 1x1 |
A synthesized luminance frame was built by adding all frames together, then applying DDP and a touch of sharpening. The original RGB frames were then blurred a bit to smooth them. Photoshop was then used to merge the L and RGB color data.