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Image Details: M081 - Bode's Nebula

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M081 - Bode's Nebula

Object/Name: M81 (NGC 3031, PGC028630) Image Details:
Type: Galaxy (Sb) Luminance IRB:5.00 min. (42) – 210.00 min. 1x1
Constellation: Ursa Major Red:5.00 min. (6) – 30.00 min. 1x1
RA: 09 hours 56.6 minutes Green:5.00 min. (6) – 30.00 min. 1x1
Dec: +69 degreees 04 minutes Blue:5.00 min. (2) – 10.00 min. 1x1
Distance: 4.5 million light years Total Time:280 minutes
Magnitude: 6.9 mag   
Size: 14.1 x 26.9 arc minutes   
Imaging Dates: 24 December 2006 - 20 March 2007   
Location: Dark Horse Observatory, Kimberton, PA 19460 U.S.A.   
Telescope: Takahashi BRC-250 Mount: Mountain Instruments
CCD: SBIG ST-10XME Rotator: Optec Pxyis Rotator
Focuser: Finger Lakes Instruments DF2 Filters: Astrodon Series E
Software Used:
  CCDStack MiraPro Professional
Photoshop CS2 Russel Croman’s Gradient Xterminator
Noel Carboni’s Astronomy Tools  
Detailed Information:
The pronounced grand-design spiral galaxy M81 forms a most conspicuous physical pair with its neighbor, M82, and is the brightest and probably dominant galaxy of a nearby group called M81 group. A few tens of million years ago, which is semi-recently on the cosmic time scale, a close encounter occurred between the galaxies M81 and M82. During this event, larger and more massive M81 has dramatically 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 lower left of the nuclear region. The galaxies are still close together, their centers separated by a linear distance of only about 150,000 light years.

M81 is the first of the four objects originally discovered by Johann Elert Bode, who found it, together with its neighbor M82, on December 31, 1774. Bode described it as a "nebulous patch", about 0.75 deg away from M82, which "appears mostly round and has a dense nucleus in the middle," and included it as No. 17 in his list. Pierre Méchain independently rediscovered both galaxies as nebulous patches in August 1779 and reported them to Charles Messier, who added them to his catalog after his position measurement on February 9, 1781.

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