M81 (Bode's Galaxy) and Holmberg IX

All Images Copyright Steve Cannistra

Please click here or on image for a higher resolution view.

Magnitude:  6.9
Size: about 21' x 10'
Distance: 12 million light years
RA: 9h 55m 58s
Dec: 69 degrees 02' 43"

M81 is a grand-design spiral galaxy that was discovered by Johann Bode in 1774.   Due to its relatively large size and high surface brightness, it is an easy target for visual observation through small aperture telescopes.  M81 forms a galactic pair with M82 (not shown), located only 150,000 light years apart, and the two galaxies have influenced each other through a close encounter occurring tens of millions of years ago.  Closer examination of this image reveals several other small galaxies, as well as a larger companion galaxy just to the left of M81, referred to as Holmberg IX.  Also notice the subtle, linear dust lane that courses through M81, seen just above the galactic nucleus, that is thought to be the result of a past interaction with M82.  More information about M81 may be found here.

Photographic Details:

Date:  December 7, 2004.
Takahashi Epsilon 250mm aperture, F/3.8 astrograph (850mm focal length) mounted on a Paramount GT1100ME mount, located in an observatory near Mahill, New Mexico.  I accomplished scope/autoguider set up and image acquisition by remote control over the internet from my home in Needham, MA.  A zip file of the raw subexposures was downloaded after completion of the session, ready for processing.  Scope time was rented through Rent-A-Scope.
Camera and autoguider: 
ST-8XE CCD camera (NABG).
Filter:  Custom Scientific Clear filter.
Exposures:  Luminance: 88' total (22 x 4'), unbinned.
Conditions:  Clear skies in New Mexico.  Cloudy in Massachusetts.
Blooms were removed using Ron Wodaski's DeBloomer plug-in for Maxim. 
All images were then dark, bias, and flat frame calibrated.  Alignment done in MaximDL.  Sigma combined using RC Sigma Reject plug-in for Maxim.  DDP and gradient correction performed in ImagesPlus (IP).  Subsequent processing including levels and curves adjustments in Photoshop CS (16 bit format).  Final sharpening with Lucy-Richardson deconvolution in ImagesPlus, followed by an unsharp mask in PS.  This is a work in progress- I eventually plan to make a composite color image that includes both M81 and M82, with a widefield background obtained through my Sky90/SXV-H9.
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