M81 (Bode's Galaxy) and Holmberg IX
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.
Date: December 7, 2004.
Scope: 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'),
Conditions: Clear skies in New Mexico. Cloudy in
Post-processing: 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.
combined using RC Sigma Reject plug-in for Maxim. DDP and
gradient correction performed
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
note: Graphics on this website
may not be reproduced without author permission.
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