Planetary Nebula Abell 4

Abell 4
Abell 4: Planetary Nebula with Galaxy; 500 mm Cassegrain f=5800 mm f/11.4 + SBIG STL11K; 60+10+10+10 min LRGB; Bernese Highlands; © 2005 Radek Chromik [32]


The planetary nebula Abell 4 (PN A66 4, PK 144-15.1) was discovered in 1964 by the American astronomer George Ogden Abell on the photo plates of the «Palomar Observatory Sky Survey» (POSS). Most of these 86 PNs discovered on the POSS photo plates are large and have a low surface brightness, which suggests that their stage of development is advanced. Abell described the PN as a homogeneous disk with a diameter of 20". [332]

Physical Properties

The PN is located at a distance of 5621 parsecs, which corresponds to around 18,300 light years. The apparent brightness in the B filter is given as 15.6 mag. [145]

The weak edge-on galaxy 2MFGC 2191 is located about 45 arc seconds next to the PN. The apparent brightness in the 2MASS JHK filter is: J 13.4 mag, H 12.5 mag, K 12.1 mag. [145]

Further infos at CDS: PK 144-15.1, 2MFGC 2191

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
Designations PN G144.3-15.5: A 4, PK 144-15.1, ARO 205, VV' 13
Right Ascension (J2000.0) 02h 45m 26s
Declination (J2000.0) +42° 32' 36"
Dimensions 20." (optical)
C-Star Designations AG82 15
C-Star Magnitude B: 19.9
Discoverer ABELL 1964

Finder Chart

The planetary nebula Abell 4 is located in the constellation Perseus and is circumpolar for Central Europe. The best observation time is August to March. The open star cluster Messier 34 serves as a guide. Almost 1° to the east of this is a small diamond-shaped formation made up of four little stars (dragon square). If you hop back three asterisks from there in the direction of M 34, you will get to Abell 4.

Finder Chart Planetary Nebula Abell 4
Planetary Nebula Abell 4 in constellation Perseus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

400 mm Aperture: The position of Abell 4 can be clearly determined using the location card with a 21 mm Ethos eyepiece (85x). However, the PN itself does not remain visible. Only at a higher magnification with a 9 mm Nagler (200x) does the planetary nebula reveal itself and is with indirect vision only barely recognizable as a faint, round nebula about half the size of Jupiter. Nothing can be seen of the galaxy 2MFGC 2191 right next to it. — Taurus T400 f/4.5 Dobsonian, Hasliberg Reuti, 6. 11. 2021, Bernd Nies

762 mm Aperture: The PN is clearly and directly visible in the 13 mm Ethos eyepiece (193x). Only the core of the galaxy right next to it can be seen. One thinks to see the central star of the PN flashing briefly from time to time, but that was probably more of an imagination. This could not be confirmed at a higher magnification in the 9 mm Nagler (280x). Eventually that was due to the rather modest seeing at night. — 30" f/3.3 Slipstream Dobsonian, Hasliberg Reuti, 6. 11. 2021, Bernd Nies

Objects Within a Radius of 15°