Object: Constellation: Coordinates: Size: Brightness:
Messier 17
(cluster = NGC 6618)
Sagittarius 18h20m / -16°11' 11' 6.0mag

The H II region Messier 17 ("Omega nebula", "Swan nebula") in the constellation Sagittarius on August 3 / 4 2016 and June 7, 2014. Messier 17 is between 5000 and 6000 light-years from Earth and was discovered by Philippe Loys de Chéseaux in 1745. (source: Wikipedia).

Thirty-six exposures of approximately 3 minutes at ISO 800 were stacked with no dark frame subtraction with Deep Sky Stacker (resulting in a 1 h 56 min exposure) and further processed in Photoshop.
Equipment: Canon EOS 450D Baader modified camera, TeleVue Paracorr Type II coma corrector, 16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform, Lacerta MGEN autoguider, Lacerta off axis system (field of view comparison: image of the moon with the same equipment).

Search chart for Messier 17. Map © 2016 "The Mag-7 Star Atlas Project", www.siaris.net. Map is modified. The map can be downloaded here .