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The Trifid Nebula | by Terry Robison
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The Trifid Nebula

Messier 20, or The Trifid Nebula is an unusual combination of dark, reflective, and emission nebula, plus an interesting open cluster of stars. It is located in an H II region in Sagittarius. The distance from out vantage is around 5200 light years away. It’s a little over 21 light years across, and is fairly bright at Magnitude 6.3. This makes it a fairly popular target with amateur astronomers.


I wanted to highlight the fine Ha filaments that surround this popular target. Ha areas are typically red in astronomical photos. The central area is bright, and tends to have a more washed out colour. On closer inspection, there is a terrific amount of detail running through the lobs. It looks like there are many dark cavernous channels intersecting this area. Each branching out into tiny filaments.


Exposure Details:


Lum 46X900

Red 12X900

Green 8X900

Blue 11X900

Ha 18X1800 8


Total time 28.25 hours


Instruments Used:


10 Inch RCOS fl 9.1

Astro Physics AP-900 Mount

SBIG STL 11000m

FLI Filter Wheel

Astrodon Lum, Red, Green, Blue Filters

Baader Planetarium H-alpha 7nm Narrowband-Filter



Software Used


CCDStack (calibration, alignment, data rejection, stacking)

Photoshop CS 6 (Image processing)

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Uploaded on November 27, 2018