Galaxy M82

That same night I pointed the telescope towards the irregular Galaxy M82 (NGC 3034), in Ursa Major (Big Dipper). Its visual brightness is magnitude 8.4 and apparent dimension 11.2' x 4.3' (Uranometria 2000 2nd ed.).

For this object I enabled the telescope tracking and used a focal reducer. With the ALT-AZ mounted telescope, the longest exposure I can take in this area of the sky at this focal length (about f/6.9), without the effects of field rotation causing the stars to streak too much, is about 30 seconds. This single unguided 60 second automatically dark subtracted image is the best result of this night. The camera was cooled to -25°C.

The amorphous galaxy M82 contains a starbursting nucleus. Images in the light of ionized Hydrogen and Sulfur show vast filaments of ionized gas streaming away from the galaxy. In the image below, this ionized gas is not visible, but dark dust lanes and patches in the central part of M82 are. The central dark dust lane can be observed visually as well with the same telescope. The stars in this image are all part of our own galaxy. Their distances are up to a few hundred light years. M82 itself lies far beyond the borders of our galaxy, at a distance of about 12 million light years.

One minute exposure. Camera cooled to -25°C.