The Omega Nebula, M17

The Omega Nebula, aka the Swan Nebula, Checkmark Nebula, Lobster Nebula, and the Horseshoe Nebula, catalogued as Messier 17 or M17 or NGC 6618 is an H II region in the constellation Sagittarius.

It is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. The total mass of the Omega Nebula is an estimated 800 solar masses.

It is considered one of the brightest and most massive star-forming regions of our galaxy. It's local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on.

The main version is not colour calibrated, it just has had the RGB histograms aligned, the second PCC version has had Photometric Colour Calibration applied. Both version's star colours are from the PCC version.