M20 – The Trifid Nebula in Sagittarius

Telescope: LXD75 SC8 @ f/6.3, LX65 mount, altaz mode

Camera: Baader modified Canon 600Da, interval timer

Filter: GSO IR Blocking Filter

Guide scope: None

Exposure: 36x10sec, ISO 1600, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/25sec, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency, moonlight

Lensed Sky Quality Meter: 18.3

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Deep Sky Stacker, Nebulosity, Photoshop

M20, the Trifid Nebula in Sagittarius is one of a series of nebula that grace the summer Milky Way. The red is a tenuous cloud of interstellar hydrogen set aglow by stars embedded in it, the blue is dust in the background reflecting starlight, and the dark lanes are vast streamers of dust in the foreground. Being near the Milky Way this field is crowded with faint stars, though the density of stars is uneven. The dark regions show areas of dust blocking the light from the faint distant stars in the background while the brighter regions are relatively clear avenues into the deep galaxy beyond.

This is one of a series of images that I have been taking to explore using relatively simple equipment and techniques. M20 is one of several examples of nebula that are utterly invisible from my backyard, even in my 16.5”, but are within easy reach of modest imaging equipment. For me, imaging is primarily an extension of visual observing and while the product is a photograph, the thrill is observing targets that are otherwise invisible.

M20 is currently low in the southwest at sunset.