Messier 17 is a large, bright emission nebula and dark nebulae complex in Sagittarius.

M17 has a number of popular names, including the Omega Nebula, Swan Nebula, Checkmark Nebula, Lobster Nebula, and Horseshoe Nebula.

After M42, the Omega Nebula is the brightest galactic nebula in the northern sky. It is located just to the north of M24, the Small Sagittarius Star Cloud, in the summer Milky Way.

M17 can be easily seen in binoculars and in a telescope the brighter portion of the nebula has the very distinctive shape of a swan, or the Greek letter Omega, hence its popular names.

M17 shines at 6th magnitude and is cataloged with a size of 11 x 11 arcminutes, but is much larger in long-exposure images. It is located at a distance of 5,500 light-years.

Philippe Loys de Chéseaux discovered M17 in 1764, and Charles Messier independently observed it and listed it in his catalog in the same year. In 1893, Isaac Roberts took the first known photograph of M17 with a 20 inch reflector and a two-hour exposure.

North is to the bottom in the above image.

Messier 17 Catalogs: M17, NGC 6618 Common Names: Omega Nebula Swan Nebula Checkmark Nebula Lobster Nebula Horseshoe Nebula Object Type: Emission Nebula Magnitude: 6v Size: 11' x 11' Constellation: Sagittarius Image Field Centered At: RA: 18h 20m 51s Dec: -16° 10' 54"