M 16 - Trifid Nebula (NGC 6618)
Messier 20 or M20 (also designated NGC 6514) is a nebula and star cluster in the constellation Sagittarius. It has an apparent visual magnitude of 9 and its angular diameter is 28 arc-minutes. M20 lies at an estimated distance of 5200 light years. The Equinox 2000 coordinates are RA= 18h 02.6m, Dec= -23° 02´ which makes M20 best seen during the summer. The Messier Summer Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Trifid Nebula.
This nebula and star cluster were discovered by Messier in 1764 although he failed to detect the nebulosity. The Trifi Nebula is remarkable for the three-lobed appearance of its hydrogen emission nebula as well the nearby blue reflection nebula. According to Kharchenko et al. (2005), the distance of M20 is 2660 light years and its diameter is 15 light years. It contains >120 stars and its estimated age is 0.3-0.4 million years.
For more information, see the Messier Catalog as well as specific entries for M20 in Wikipedia and SEDS.
Messier's Description of M20
June 5, 1764
`Cluster of stars, a little above the Ecliptic, between the bow of Sagittarius
and the right foot of Ophiuchus. Reviewed on March 22, 1781.'
[see also description of M21]
Technical Details
- Object: M20 - Trifid Nebula
- Other Names: NGC 6514, Trifid Nebula
- Object Type: nebula and star cluster
- Object Data: Apparent Magnitude = 9, Angular Size = 28 arc-minutes
- Object Position (Equinox 2000): RA= 18h 02.6m, Dec= -23° 02´, Constellation = Sagittarius
- Date: 2021 Jul 09-13, and Jul 15 (6 nights)
- Location: Chile Remote Observatory, Observatorio El Sauce, Chile
- Partnership: Operated in partnership with David Churchill
- Telescope: Planewave CDK-17 (with Focal Reducer: f/4.5; FL = 1945mm)
- Camera: QHY 16200A with Integral 7-position Filter Wheel
- Mount: Astro-Physics 1600GTO
- Guider: Agena Starguide II / SBIG STi
- Sub-Exposures: Astronomik Filters
- Luminance: 102 x 5 min = 510 min
- Red: 48 x 5 min = 240 min
- Green: 48 x 5 min = 240 min
- Blue: 48 x 5 min = 240 min - Total Exposure: 20h 25m
- File Name: M20-CDK21-C01w.jpg
- Field of View: 38.9' x 58.3' at 0.64 arc-sec/pixel
- Original Image Size: 3630 x 4540 pixels (16.5 MP); 12.1" x 15.1" @ 300 dpi
- Data Acquisition: David Churchill
- Image Processing: Fred Espenak
- Maxim DL: Image Calibration, Stacking, Log Stretch
- Adobe Camera Raw: Noise Reduction, Color/Contrast Adjustments
- Photoshop CC: Curves, Levels, Hi Pass Filter
- Topaz Labs: Sharpen AI - Copyright: Fred Espenak