M81 & 82 – Spiral Galaxies in Ursa Major

Telescope: Meade SN10 at f/4, Orion Atlas EQ-G

Camera: Full Spectrum Modified Nikon D810

Filter: GSO IR Blocking Filter

Guide scope: Williams Optics 50mm, ASI290MM mini, PHD

Exposure: 154x20sec, ISO 200, saved as RAW

Darks: Internal (Long Exposure Noise Reduction)

Flats: 32×1/50sec, tee shirt flats taken at dusk

Average Light Pollution: Red zone, fair transparency

Lensed Sky Quality Meter: 18.5 mag/arc-sec^2

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard Nikon, Nebulosity, Deep Sky Stacker, Photoshop

This is M81 (bottom) and M82 (top), two bright spiral galaxies lying about 12 million light years away in Ursa Major. At present, 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. To the lower left is the small spiral galaxy NGC 3077. This galaxy is about 19,200 light years across and 13 million light years distant.

M81 and M82 are currently high in the northwest at dusk.