Messier 109 (Ursa Major)

Object image
Fig.1 - A "Theta" made of stars: The barred spiral galaxy Messier 109 in Ursa Major, photographed with a 16-inch f/4.5 Dob on an equatorial platform. The bright central bar together with the fainter spiral arms around it give the galaxy the appearance of the Greek letter "Theta" (Θ).
Object name: Constellation: Coordinates: Apparent size: Visual brightness:
Messier 109 (NGC 3992) Ursa Major 11h58m / +53°22' 7.5' x 4.4' 9.8 mag

The barred spiral galaxy Messier 109 (also known as NGC 3992) in the constellation Ursa Major. Messier 109 is around 84 million light-years from Earth and exhibits a weak inner ring structure around the central bar. The galaxy was discovered by Pierre Méchain in 1781. (source: Wikipedia).

Forty-five 3-minute exposures (135 minutes total exposure) at ISO 800 taken on March 15, 2020 were added for this shot with the DeepSkyStacker software and the final image processing was done 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
Fig.2 - Search chart for Messier 109. Map © 2021 "The Mag-7 Star Atlas Project", Map is slightly modified. The map can be downloaded here.