Object: Constellation: Coordinates: Size: Brightness:
M 33
(= NGC 598)
Tri 01h34m / +3040' 70' x 40' 5.7mag

The spiral galaxy Messier 33 (Triangulum Galaxy, NGC 598) in the constellation Triangulum on October 9 / 10, 2015. The galaxy is approximately 3 million light years from Earth and was probably discovered by the Italian astronomer Giovanni Battista Hodierna before 1654 and independently discovered by the French astronomer Charles Messier in 1764.

With a diameter of 50'000-60'000 light years, Messier 33 is the third-largest galaxy of the Local Group of galaxies (the "local" galaxy group that includes the Milky Way, the Andromeda Galaxy and more than 50 other "neighbouring" galaxies). It is one of the most distant objects that can be viewed by the naked eye. (source: Wikipedia)

Nine-teen exposures of approximately 3 minutes at ISO 800 with no dark frame subtraction were stacked with Deep Sky Stacker (resulting in a 1 h 2 min exposure) and further processed in Photoshop. Dew on the secondary mirror and haze limited the depth of the final image.
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 33. Map © 2015 "The Mag-7 Star Atlas Project", www.siaris.net. Map is modified. The map can be downloaded here .