Planetary Nebula Abell 71
The planetary nebula Abell 71 (PK 85+4.1) was discovered in 1955 by the American astronomer George Ogden Abell on the photo plates of the Palomar Observatory Sky Survey (POSS). In 1955 he published a first list of 13 globular clusters and the positions of 73 planetary nebulae. The PN had the number 58 (A55 58). Stewart Sharpless added the nebula to his catalog of H-II regions as Sh2-116 in 1959. Due to its size and low brightness, it probably did not recognize it as a planetary nebula. In 1966 Abell published a complete list including the size and description of the 86 planetary nebulae discovered on the POSS photo plates. The designation PK 85+4.1 originates from the two Czechoslovak astronomers Luboš Perek and Luboš Kohoutek, who in 1967 compiled a catalog of all the planetary nebulae of the Milky Way known at the time. [331, 332]
Abell 79 is very large with an angular diameter of around 2.6 arc minutes, but has a very low surface brightness with 19 magnitudes. This suggests an advanced age. The distance was determined to be 729 parsecs (around 2400 light years) in 2008. 
|Designations||PN G084.9+04.4: A 71, PK 85+04.1, A55 58, ARO 352, Sh 2-116, VV' 537|
|Right Ascension (J2000.0)||20h 32m 23s|
|Declination (J2000.0)||+47° 21' 04"|
|Expansion Velocity||10. km/s (O-III), 20. km/s (N-II)|
|C-Star Designations||AG82 412, CSI +47 -20308, UBV 17830|
|C-Star Magnitude||18.66 mag (U filter), 19.32 mag (B filter), 18.95 mag (V filter)|
The planetary nebula Abell 71 is located in the constellation Cygnus (swan). The best observation time is April to November.
Description pending ...