Here is the luminance data from this color image processed in a way that better reveals extremely faint objects. Arp's Loop can easily be seen as a broad irregular ring of material encompassing the right hand side (northern portion) of M 81's spiral disc, while a portion of the loop's dust can even be seen in projection against the the galaxy's disc just to the lower right of the bright core. This particular feature is commonly captured on other deep photographs of M 81 as a rather odd set of dark absorption lanes crossing the disc of M 81 just to the northwest of the galaxy's central bulge. The faint loop was discovered in 1965 by Halton Arp using a 48-inch Schmidt telescope and is estimated to glow at merely .5% brighter than the dark nightime sky, itself! Arp's Loop is thought to be the result of tidal effects from the close encounter of the galaxies Messier 81 and Messier 82 more than 200 million years ago. It has been known since 1986 that the loop is composed of gas, dust, and star-like objects. More on recent observations of Arp's Loop using Hubble Space Telescope can be found by clicking here .Also of note in this highly stretched image are several faint wisps of high-altitude galactic cirrus nebulosity, especially to the lower right of M 82. These are thought to be relatively warm, low density strands of faint reflection nebulosity and are proven to be part of our very own Milky Way galaxy. More of this type nebulosity can be seen here. Image above taken with homemade 8-inch f/5.4 astrograph and SBIG STL-11000M with exposures totaling 140 minutes.