CCD image taken with an STL-1301E CCD camera thru our 20-inch F/8.1 telescope working at F/5. The field of view is about 20x25 arc minutes.
M-17 is a bright emission nebula in Sagittarius. It is known as the "Omega Nebula" or the "Swan Nebula". Swiss astronomer Philippe de Cheseaux discovered M-17 in 1746. Charles Messier re-discovered it 1764. Sir William Huggins, in 1866, was the first to study the light of M-17 with the spectroscope; he announced that the cloud was truly a mass of glowing gas, and not merely an unresolved cluster of stars. The Kopernik image above only shows the bright central 8' x 8' arc minute portion of the nebula. One of the largest of the nebulae, M-17 covers about 46 x 46 arc minutes.
P. de Cheseaux: (1746) ''A nebula which has never been discovered: it has a shape quite different from the others: it has the perfect form of a ray or the tail of a comet, 7' long and 2' wide. Its sides are exactly parallel and quite well terminated. The center is whiter than the edges. It makes an angle of 30° with the meridian.'
C. Messier: (June 3rd, 1764) 'A train of light without stars, 5' or 6' in extent, in the shape of a spindle, a little like that in Andromeda's belt (M 31) but the light very faint. In a good sky, seen very well in a 32-foot telescope. Diameter: 5 arc minutes.'
Quote from Burnham's Celestial Handbook:
'For the visual observer, the main feature of M-17 is the long bright comet-like streak across the north edge; on the west end a curved 'hook" gives the whole nebula a resemblance to a ghostly figure "2" with the bright streak forming the base. It requires only the slightest use of the imagination to transform this pattern into the graceful figure of a celestial swan floating in a pool of stars.......The space enclosed by the neck of the swan is evidently an obscuring cloud of some sort, and looks quite dark when compared to the star-strewn sky beyond. Fainter luminous masses extend to the east and north, forming an irregular loop around the whole structure......'
George Normandin, KAS
November 12th, 2007