M17 Swan Nebula In Sagittarius

On a warm summer night looking south from a dark sky location, we can imagine a mythical creature straddling the celestial river (Milky Way): a half-man, half-horse Centaur, which represents the constellation of Sagittarius (The Archer). Hidden among the dust lanes of our Galaxy’s spiral arms and placed at about 5,500 light years away, there is a cloud made of gas and dust that can be even seen with unaided eye or better with a pair of binoculars. This is entry #17 on Charles Messier catalogue of deep sky objects, also known as the Omega nebula (last letter of the Greek alphabet), the Swan nebula, the Checkmark nebula, the Lobster nebula or the Horseshoe nebula.

Astronomers besides calculating its distance are also telling us that the Swan nebula is a region in space consisting mainly from Hydrogen gas (HII region) and that it contains many young stars hidden inside (a stellar nursery, like the better known Orion nebula), that emit radiation and triggering the hydrogen atoms of the nebula to shine with its characteristic red light.

This image of the Swan nebula was taken with a small refractor telescope and a DSLR camera (see details below) and besides the main nebula it also reveals other wisps of nebulosity close by and of course the numerous stars of our Galaxy placed much closer to us than the nebula itself.

So, what’s your favorite nickname for this object?

Telescope: Orion EON ED 80/500 refractor

Mount: Modified Vixen Sphinx

Camera: Canon EOS 20Da

Filter: Astronomik CLS

Guiding: Skywatcher 80/400 refractor, Skywatcher Synguider

Light frames: 5 x 5 mins (total: 25 mins), ISO 1600, Custom WB, calibrated with darks

Date & Location: 2/9/2019 - Chalkidiki, Greece

Processing: DSS 4.2.3, Adobe Photoshop 2020 with Astronomy Tools Actions Set (spikes added to the brightest stars), finished in Lightroom CC