The Trifid Nebula (M20): H-alpha, O3, and Blue
This is a beautiful object found in the southern summer milky way above Sagittarius, and features a bright blue 
Reflection Nebula next to a bright red emission nebula. I am coming back to it after about 5 years (see image below) and hitting it with my new & improved equipment & techniques. This image is processed to highlight the faint hydrogen alpha emissions in the area, which are clearly seen in the lower left and right. (Using a H-alpha filter on a monochrome camera is the most efficient way to capture this kind of low-level detail. Scroll down to see the H-alpha component.)
The original Star Trek series used an image of the trifid nebula as a background of one of it's special effects. The episode was "The Alternative Factor", Whenever Lazarus changed universes, a picture of the Trifid Nebula was seen.
Image Details: This is an experimental image I assembled from the following filtered frames on my monochrome camera: 14 H-alpha as Red, 9 O3 as Green, and 9 Blue as Blue. Each exposure was 5 minutes unbinned; total exposure time was 160 minutes or 2 and 2/3 hours. The biggest processing challenge was the very big/blue stars that resulted from using the blue luminance filter. I performed various tricks to mitigate that to a modest degree of success at best. All images were acquired during my Spring 2011 Davis Mountains trip. Takahashi TOA 130 (a 5" APO refractor) with reducer, Astro-Physics AP 900GTO mount, SBIG ST-8300M (monochrome) camera, Astrodon filters. See my primary Narrowband page for more info on narrowband filters & imaging.
This more traditional-looking M20 is from May, 2006.
Image notes: Images from the "Starry Nights" Bed and Breakfast near Wimberley, TX, taken May 20, 21st, and a bit into the morning on the 22nd. Conditions were challenging. I shot this low on the SE horizon as it rose, while all around thin clouds came and went. I ended up with 19 usable frames (x 4min = 76min total exposure). Things went from pretty good to totally clouded out very abruptly at 2:50 a.m. on the 22nd. Takahashi TOA 130 (a 5" APO refractor) and Canon EOS D20a. See my May 2006 Starry Nights page for more.
This is the H-alpha component of the top image. Spring 2011 Davis Mountains trip. Takahashi TOA 130 (a 5" APO refractor) with reducer, Astro-Physics AP 900GTO mount, SBIG ST-8300M (monochrome) camera, Astrodon filters. See my primary Narrowband page for more info on narrowband filters & imaging.
| M20 and M8 area |  Close-up Picture of the Trifid Nebula, M20, with intense colors |
| Trifid Nebula (M20) and Star Cloud (M24) Pictures |  Check out: Wider views ofTrifid and M8 - includes area object links |
| Trifid Nebula, M20, and M8, Visual Index | Trip Pictures 2 |
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Houston Astronomical Society (HAS) home page
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