The Omega Nebula, also known as the Swan Nebula, Checkmark Nebula, Lobster Nebula, and the Horseshoe Nebula (catalogued as Messier 17 or M17 and as NGC 6618) is an H II region in the constellation Sagittarius. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier catalogued it in 1764. It is located in the rich starfields of the Sagittarius area of the Milky Way.
The Omega Nebula is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud ofinterstellar 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.

Imaging telescopes or lenses: GSO Newton 12″ f/4
Imaging cameras: ATIK 11000m
Mounts: Skywatcher EQ8
Guiding telescopes or lenses: Orion 50 mm mini guider
Guiding cameras: Orion Star Shoot Planetary Imager & Autoguider
Focal reducers: ASA Wynne 3″ Corrector 0.95x
Software: photoshop, Startools 1.3.5, CCDStack, Maxim DL
Filters: Orion 2” LRGB filter set, Baader Ha 2″
Dates: June 6, 2014
Frames:
Orion 2” LRGB filter set: 9×300″ -15C bin 2×2
Baader Ha 2″: 4×600″ -15C bin 1×1
Integration: 1.4 hours

Author: Paul Storey
AstroPhotography of the day by SPONLI 18 July 2014