M81 (Bode's Galaxy) and M82 (Cigar Galaxy)

M81 and M82
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 (the larger galaxy on the right) 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 (on the left), 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 a larger companion galaxy just to the bottom of M81, referred to as Holmberg IX.  More information about M81 may be found here.   M82 (the smaller galaxy on the left) is a companion to M81 and was also discovered by Johann Bode in 1774.  It has an odd, oblong shape that is thought to have arisen from gravitational interaction with M81 millions of years ago.  High resolution color images of M82 show dramatic tendrils of red gas shooting from the center of the galaxy.

Photographic Details:

Date:  December 7 and 11, 2004 (for M81 and M82 luminance, respectively).   January 10, 2005 (widefield luminance, RGB, and Ha data).
January 10, 2005:  Takahashi Sky 90 at f4.5 with field flattener/focal reducer, on the G11 Losmandy Mount.  The December 7 and 11 luminance images were taken remotely using a Takahashi Epsilon 250mm scope at New Mexico Skies (details found at M81 and M82, respectively).
Autoguider:  SBIG STV with e-finder.
Camera:  SXV-H9
Astronomik Ha filter (13 nm bandpass); Type II R, G, B, plus clear filter set.
Exposures:  L:(HaR:G:B).  205' for Luminance (includes all luminance data from 12/7/04, 12/11/04, and 1/10/05); 30' for Ha; 20' each for R, G, and B, all unbinned.  Total exposure time about 5 hours.
Conditions:  (January 10, 2005) Temperature 36 degrees F; average transparency; average seeing; a bit breezy.
Alignment done in ImagesPlus.  Sigma combined using RC Sigma Reject Plug-in for MaximDL.  DDP was performed in ImagesPlus (IP).  Subsequent levels and curves adjustments in Photoshop CS (16 bit format).  The red channel was comprised of an Ha:R mix (100% opacity for R using lighten mode) in order to highlight the HII regions in the final image.

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