M51 (NGC 5194/5), The Whirlpool Galaxy,
in Canes Venatici — CCD Images
M51, with its small companion galaxy NGC5195 (left, North), is one of the most famous and certainly one of the most beautiful galaxy pairs in the northern sky. Although about the same size as the Milky Way and the Andromeda galaxy, it is about 37 million ly distant, and therefore quite small. Several knots of reddish hydrogen-rich star-forming regions can be seen in the spiral arms. (Note that much faint "nebulosity" around the smaller galaxy will only be visible on a monitor in a darkened room.) As suggested by the number of images on this page, M51 is a tricky target—it's easy to get an image of it but difficult to get (and process) a good image. North is to the left in these images. Note the two tiny additional galaxies (small smudges) below (about 7 o'clock) and to the left (about 8 o'clock) of the main pair.
As you can see from the three images below from 2002, this has been a work in progress. These were among my first partially successful CCD images, and replaced a low resolution film image taken in 2000. Processing CCD images is, I find, a much more subjective process than processing film images. The first image below was generated from CCD images captured on 2002-04-13 and was composed using AIP4WIN to enhance the luminance image, MaxIm to combine the RGB, and Photoshop to add a single luminance layer. Though the image is somewhat overprocessed, the duration of the luminance images was greater and the resulting image is sharper. The middle image (LLRGB), was constructed using Rob Gendler's method. The problem of preventing a burned-out core while bringing up the fainter arms is well-illustrated by this series and—from the above image—is still not completely under control.