M81 & 82 – Spiral Galaxies in Ursa Major

Telescope: Meade N6 at f/5, Orion Atlas EQ-G
Camera: Full-spectrum Modified Canon 600D, Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro III, PHD
Exposure: (59+41)x120sec ISO 800 saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flat: 32x1/250sec, ISO 800, tee shirt flats taken during twilight
Average Light Pollution: Red zone, fair transparency (both nights)
Lensed Sky Quality Meter: 18.5-18.7 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard EOS, Nebulosity, Deep Sky Stacker, Photoshop

This is M81 (bottom) and M82 (top), two bright spiral galaxies lying about 12 million light years away in in Ursa Major. At present, the these two galaxies are about 150,000 light years apart, though a few hundred million years ago the two passed very close to each other. The dark dust lane slashing across M82 is one result of this close encounter with M81 as are the blue star formation regions in M81.

The source images for this field were collected over 2 evenings; 59 on 11/23 and 41 on 11/25. The sky conditions were a bit variable, and I suspect that the passing haze illuminated by my local skyglow (a soupy reddish greenish) robbed some of the color out of the source images. I’ll have to give this another try once my ZWO ASI071MC Pro arrives.


M81&82 (11-23&25-2017)-2j.jpg