George Abell's examination of the Palomar Observatory Sky Survey in the mid 1960's yielded 86 planetary nebulae which have proven to be an
observer's dream challenge, for many of these celestial objects are not only very faint in magnitude even under very dark skies but are also
relatively large with dimensions often measured in minutes in lieu of seconds. Later analysis of Abell's catalog revealed that at least four
of these objects, namely Abell 11, 32, 76 and 85, are not planetary nebulae at all. For the avid observer, an O-III filter is highly
recommended in order to have any hope of visually detecting these elusive wonders.
An even greater number of planetary nebula can be found within the NGC and IC catalogs and are available elsewhere on this site (see here). As is evident from the image below, planetary nebulae are beautiful to look at thanks to the glowing and colourful gaseous shrouds which make their planetary appearance and colouration possible as a result of stars having exhausted their nuclear material and having reached the last stages of their life. Some of the more exotic planetary nebulae include the Cat's Eye (NGC 6543), the Saturn Nebula (NGC 7009), the Ghost of Jupiter (NGC 3242) and the Owl Nebula (M97).
Note: The planetary nebula Abell 71 is one of four such Abell nebulae in the constellation of Cygnus. It is second only to Abell 61 with respect to apparent diameter amongst the four Cygnus Abell planetaries and is perhaps the most dificult to observe thanks to a very dim surface brightness of 17.0 mag/arc-min2. As indicated by the image below, it is comprised of an irregular disk which is slightly elongated and measuring 168" by 147" with no distance estimate available in the academic literature. In a 1991 study by Pismi et al, it was suggested that Abell 71 is not a planetary nebula but simply an area of H-II emission.
Please click on either image below to display in higher resolution (1200 x 900)
RA / Dec:
20h 32' 23.15" /
+47° 21' 04"
168" x 147"
July 11-12, 2010
22:40 - 03:40 UT+3
AP 160 f/7.5 StarFire EDF
AP 1200GTO GEM
Baader 7nm Ç-á
SBIG LRGB + IR-block
1.16" per pixel