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M81

Messier 81
Bode's Galaxy
Spiral Galaxy
Right Ascension 09h 55m 33s Best Seen 1/1-12/15
Declination 69° 03' 55" Magnitude 6.9
Constellation Ursa Major

Actual		 Compared
to Milky Way
Distance 12 million ly --
Actual Brightness 20 billions suns --
Diameter ~95,000 ly ~0.95
Mass 250 billion suns --
Galactic Type Sb Sbc

What To Look For Through The Telescope

  1. Recommended eyepiece: 40 mm on 16 inch, 32 mm on 6 inch.

  2. When people look through the telescope they should see a fuzzy patch of light. This is the galaxy. If they are having trouble seeing it, have them look at a star near the edge of the field, then look back to the center out of the corner of their eye.

  3. The view through the telescope will not look like photographs of galaxies they may have seen. A photograph of a galaxy may have an exposure of many hours. This long exposure brings out the spiral arms and other details. Our eyes allow light to collect for only about 1/30 of a second before they refresh themselves and start over again.

M81 Information

  1. Johann Bode discovered this galaxy and its neighbor, M82, on December 31, 1774. Pierre Méchain independently rediscovered the two galaxies in 1779, and reported them to his friend Charles Messier. Messier included them in his famous catalog after he measured their positions on February 9, 1781. (M82 is an irregular galaxy.)

  2. Recently in this galaxy’s history – a few tens of millions of years ago – a close encounter occurred between M81 and M82. A trace of the encounter can be seen: a straight, dark dust lane can be seen in M81's disk.

  3. This galaxy is one of the most easiest and rewarding to amateur astronomers because it is visually bright enough to see in small telescopes. At least four observers have reported seeing this galaxy with the unaided eye under very good viewing conditions.
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References
Item Updated Notes
Coordinates 2003-01-15 tweaked with SIMBAD and SEDs
Distance 2003-01-15 previously 11 millions light years... This was Wendy Freedman and team’s results of Cehpeids pre-Hubble upgrade in 1993... with new Hipparcos info, distance to Cepheids is 12 million ly, see http://messier.seds.org/m/m081.html
Actual Brightness 2003-01-15 can find no support for this, PLUS, most other spiral galaxy pages say same thing
Diameter 2003-01-15 previously 150 thousand ly – BUT this site says about 70,000 ly http://www.astronomy images.com/images/Galaxies/m81 82.htm University of Leicester site says 36,000 ly http://www.star.le.ac.uk/astrosoc/whatsup/galaxies.html and this site says about 40,000 ly http://www.astrosurf.com/jwisn/m81.htm
Mass 2003-01-15 seems OK, checks with http://www.astrocruise.com/m81.htm
Galactic Type 2003-01-15 OK with SEDs site
Other Information 2003-01-15 OK with SEDs site
and http://www.messier-objects.com/messier-81-bodes-galaxy/