Planetary Nebula Abell 74
History
This planetary nebula 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 61 (A55 61). In 1966 Abell published a complete list including the size and description of the 86 planetary nebulae discovered on the POSS photo plates. This planetary nebula was then number 74 on his list. The designation PK 72-17.1 comes 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 that time. [331, 332]
Physical Properties
Abell 74 is a large and extremely faint old planetary nebula, barely detectable on the POSS red photo plates. On the image of the Mayall 4 meter telescope (Fig. 2) it looks like a twin of the Dumbbell Nebula Messier 27, but it is much much fainter. Simbad lists a B magnitude of 16.91 and a V magnitude of 17.11. The distance was determined to be 657 parsecs by Gaia Early Data Release 3 in 2020. The planetary nebula is superimposed to the faint galaxy MCG+04-50-004 which has a B magnitude of 15.0. [145]
| Designations | PN G072.7-17.1: A 74, PK 72-17.1, A55 61, ARO 193, VV' 546 |
| Right Ascension (J2000.0) | 21h 16m 52s |
| Declination (J2000.0) | +24° 08' 51" |
| Dimensions | 830." (optical) |
| Radial Velocity | +18.0 ± 4.0 km/s |
| Expansion Velocity | 27. (O-III) 26. (N-II) km/s |
| C-Star Designations | AG82 425, CSI +23 -21146, FB 176, UBV 18389 |
| C-Star Magnitude | U: 15.72, B: 16.91, V: 17.11 |
| C-Star Spectral Type | sd Op |
| Discoverer | ABELL 1955 |
Finder Chart
The planetary nebula Abell 74 is located in the constellation Vulpecula between Cygnus and Pegasus. The star patterns in the 1° closeup help to identify the position. The nebula it self is not visible to the eye and appears only after longer integration time. On 8 August it is in opposition to the Sun and crosses the meridian at local midnight. The best time to observe is March to December, when it is highest at night.
