Abell 2 & Abell 3, 20 September 2009
The Deep Sky Section of the BAA is running a project to observe planetary nebulae catalogued by George Abell in 1966 . The objects are generally very faint and were discovered on images taken with the 1.2 m Palomar Schmidt Camera as part of the Palomar Observatory Sky Survey (POSS). As such, they present an interesting challenge for a 30 cm telescope near sea level in Suffolk!
On Sunday 20 September 2009, I attempted to image Abell 2 and 3. Both are in Cassiopeia so well placed at this time of year. The images below pick out the main features of the nebulae but do illustrate how small and faint they are. Abell 2 is listed as magnitude 14.5 and is just 33x20 arcseconds, i.e. smaller than the disc of Jupiter. Abell 3 is listed at magnitude 16.0 and is clearly bigger at 60x60 arcseconds.
The full Abell catalogue, with pictures and location maps, can be downloaded from the link referenced below. The catalogue lists 86 objects, but several are either plate faults or galaxies, some are exceedingly faint, well beyond what I could hope to image, and still others are too far south. But there are still 25–30 objects worth trying to image from the latitude of Suffolk, so this is a nice project for the winter!
Incidentally the star identified in the full-scale image of Abell 3 is a suspected variable and is much brighter in my image than in Guide 7.0 planetarium software. I’m trying to find out more about it...