M51 - The Whirlpool Galaxy


M51 (NGC 5194) is a great face-on spiral galaxy with a companion. Visually it takes a dark sky to see even a hint of the spiral structure. But even short CCD exposures do OK. M51 was the first "nebula" to be seen as a spiral. It is found in the constellation Canes Venatici (the Hunting Dogs), has a magnitude of 8.4 and a size of 9.0 x 8.0 arc-minutes. The companion is NGC 5195, with magnitude 9.6 and a size of 4.5 x 3.5 arc-minutes. Center to center separation is 4' 8". They are 37 million light years way.

The image below shows many interesting features.  The pink areas in the main spiral are H2 (Hydrogen ion) emissions from star forming regions, the blue areas on the leading edges of the spirals suggest areas with new hot stars.  There is a small thin edge-on galaxy on the top left, and another small galaxy on the left edge, just up from the middle.

Taken with the 12" LX200 and ST-8E at f/6.3.  Composed from nine 150 second luminance, two 10 minute red, two 10 minute green, and three 10 minute blue frames.  All frames were binned 2x2.

Flat fielding was done prior to composition. Color balanced to 1:1:1.7.  Processed with Digital Development algorithm.

Taken on June 3, 2000 at the ARGO site.

Previous best:

A 2 minute binned exposure taken with the 416XT and 12" LX200 at f/10? in my Corvallis Oregon front yard.

Taken July 27 1997.