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M 17 (NGC 6618), Omega or Swan Nebula, in Sagittarius
M17 is a large (20 x 15 arcminute), bright (magnitude 6.0), emission nebula in Sagittarius. It is easily seen with binoculars from moderately dark sites. First discovered in 1746, its resemblance to either a swan or the greek letter omega is not obvious from its telescopic appearance. Its distance is stated to be 5000 light years from Earth. The primary wavelength emitted is the hydrogen-alpha line at 656.3 nM in the far red region. While this image is not as sharp as I would like, many chaotic, twisted strands of H-alpha-emitting gas can be seen, presumably driven by strong "solar" winds from the many hot young stars. North is up in this image.
| Date | 2002-08-09 |
| Scope |
Astro-Physics 130 EDF (f/6) refractor with ST-10XME CCD camera at -10 °C and SBIG CFW-8 filter wheel on A-P 1200 GTO mount. Separate guide scope with SBIG ST-4 guider. |
| Exposure |
Custom Scientific 3 nM H-alpha 10 x 5 min; R, G, and B 4 x 5 min SBIG filters |
| Processing |
Stacked and RGB combined in MaxIm 3.07; R=1.2, G=1.0, B=2.0 weighting. H-alpha luminance registered with RegiStar. Ha and RGB combined, stretched, and balanced in PhotoShop 7.0 |