Cookie consent


I agree
Contains:  Omega nebula, M 17, NGC 6618
Getting plate-solving status, please wait...
M17 - Omega Nebula, 


            Gary Imm
M17 - Omega Nebula

M17 - Omega Nebula

Technical card

Resolution: 3840x2560

Dates:Aug. 17, 2018Aug. 18, 2018

Astrodon Blue 31mm Gen2 I-Series: 60x30" (gain: 139.00) -10C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 60x30" (gain: 139.00) -10C bin 1x1
Astrodon Ha 31mm 5nm: 18x300" (gain: 139.00) -10C bin 1x1
Astrodon OIII 31mm 3nm: 18x300" (gain: 139.00) -10C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 60x30" (gain: 139.00) -10C bin 1x1
Astrodon SII 31mm 5nm: 18x300" (gain: 139.00) -10C bin 1x1

Integration: 6.0 hours

Avg. Moon age: 7.07 days

Avg. Moon phase: 46.65% job: 2234027

RA center: 275.260 degrees

DEC center: -16.207 degrees

Pixel scale: 0.783 arcsec/pixel

Orientation: 219.496 degrees

Field radius: 0.502 degrees

Data source: Backyard


This object is an emission nebula located 5000 light years away in the constellation of Sagittarius.

Of all of the sky objects, I believe that this one has the highest number of commonly accepted names. Focusing on the bright central portion of the nebula leads to the names of the Swan Nebula as well as the Checkmark Nebula. Focusing on the broader nebula leads to the names of the Omega Nebula as well as the Horseshoe Nebula. Which name to use? As in most decisions I make in life, I relied on the internet. The Omega Nebula was the "winner" with 100,000 search engine matches of that name, compared to 65,000 for the Swan Nebula, 15,000 for the Checkmark Nebula, and 10,000 for the Horseshoe Nebula. The Omega Nebula name originated with the famous astronomer John Herschel, who stated that "The figure of this nebula is nearly that of the Greek capital Omega, somewhat distorted and very unequally bright."

Regardless of the name chosen, this nebula is beautiful and fascinating. Thick dust clouds are both obscuring the central bright stars of the nebula and also reflecting and spreading light of other stars. The object spans a big section of the sky — its gas and dust clouds measure about 15 light-years across. This material is likely fueling the birth of new stars and this image reveals many stars in front of, in, and behind the nebula. This nebula is considered one of the brightest and most massive star-forming regions of our galaxy.

Believe it or not, I used the Hubble palette (SHO) for this object, or at least that is how it started. I have a tough time processing this object - the colors usually just sort of wash together in a bright mess. So I did some manipulation this time to create some color separation. In the final image, SII is primarily represented by red, the central white area represents the strongest OIII signal, and the strongest Ha signal is the broader blue. The colors help to illuminate the numerous twisting emission fronts that are winding their way through the area around the bright stars.



Gary Imm
License: None (All rights reserved)

Sky plot

Sky plot


M17 - Omega Nebula, 


            Gary Imm