The Sombrero Galaxy

Sombrero Galaxy (M-104), NGC 4594
Sketch and Commentary by Frank McCabe

Occasionally from my home observing site the humidity drops low enough to dramatically reduce the light scatter making it possible to observe bright galaxies. This night was one of those times.
Many of the bright galaxies of northern hemisphere springtime were visible this night and I selected the bright Sombrero galaxy in Virgo for sketching. This bright (9.0 visual magnitude), Sa spiral is just north of the Corvus border. Pierre Mechain discovered it in May of 1781 and 5 days later Charles Messier added it to his copy of the Messier catalog.
Vesto Slipher in the second decade of the 20th century measured the rotation rate and red shift of this magnificent spiral. This galaxy is receding at 1024 km/sec and is somewhere between 27.7 and 30.9 million light years distant. The nearly edge-on galaxy has a large glowing central bulge and a dark dust lane that can be detected with dark adapted vision in a 10 inch telescope. A spiral galaxy with large central bulge usually implies many globular clusters in association with that central bulge. This galaxy may have as many as 1200-2000 globulars in motions around the center. A research group led by John Kormendy in the mid 1990s discovered a super massive black hole at the core of this galaxy that measured one billion solar masses. This is a galaxy worth taking a look at on a clear night. You will find it at R.A. 12h 40 min. Dec. -11º 37min.

Sketching:
9”x12” white sketching paper; 4B graphite pencil and a blending stump made from a dowel rod; after sketching a 6” circle was cut from the sketching paper;
scanned and inverted; brightness of stars adjusted with MS Paint.
Scope: 10” f/5.7 Dobsonian: 26 mm widefield eyepiece 56x and 8 mm eyepiece 181x
Date and Time: 4-3-2008, 4:00-4:50 UT
Seeing: Pickering 7/10
Transparency: Excellent 4/5
NELM: 4.8

Frank McCabe
Oak Forest, Il. USA