SBIG ST-4000XCM
15x600sec
Imager Temp -20C
APM/TMB 130/780 with Dedicated Field Flattener
Full Frame
Link to Larger JPEG

About 600 million years ago, galaxies M81 and M82 were involved in a cosmic near miss hit and run accident. During this event, larger and more massive M81 (lower) extensively deformed M82 by gravitational interaction. The encounter has also left traces in the spiral pattern of the brighter and larger galaxy M81, first making it overall more pronounced, and second in the form of the dark linear feature in the nuclear region. The centers of M81 and M82 are only 150,000 light years apart, and they continue to interact strongly. M82 may eventually be stripped of gas and dust and become a tight and featureless elliptical.

Here's an interesting paper that illustrates the difficulties in identifying and documenting adequate data on DSO's in a time when sketching and textual description was the astronomer's only tools. Besides, it has a really wild picture of William Herschel's son John.

Taken with a glaring waxing gibbous moon, which shows that the dynamic range of the CCD allows adequate imaging even in bright moonlight. I am sure that some of the faint detail like galaxy Holmberg IX suffered for it, however (even though it's miraculous that it even showed up in these conditions).

April 4, 2009