| Planetary
Nebula
aka PNG 238.0+34.8, PK 238+34.1, Abell 33, ARO 65 RA: 09h39m09.2s Dec: -02°48'35" (Hydra) Integrated Visual Magnitude: 13.4 Angular Diameter: 4.5' Mean Surface Brightness: 25.3 Mag/arc-sec² Distance 2700 ly Minimum requirements to detect: 8-inch and OIII filter under country skies |
Abell 33 is a large round planetary nebula that lies very close to a 7th
magnitude star. An OIII or UHC filter really helps bring it out.
Once the bright star (HD 83535) has been located, look to the northeast
for a very faint glow. Use low magnification (less than 100x).
Stathis Kafalis reports seeing a "Faint diffuse homogenous glow" in a 10-inch at 93x with OIII filter. Dave Aucoin detected it in a 13.1" with averted vision and UHC filter.
The best view in my 18-inch came at 94x with an OIII filter in place. It appeared as a big round glow with one edge intersecting the bright star. The glow appeared faint, but averted vision was not required to see it. If it weren't for the bright 7th magnitude star nearby it would be much easier to detect. I was able to detect the glow without the OIII filter, but this required some work and averted vision. The edge of the glow appeared neither sharp nor diffuse. The impression of a darker center was quite strong, although I could not pin it down for certain. Apparently I wasn't seeing things because Steve Gottlieb also notes that it appears to have a "slightly darker center (partially annular)."
The field in an 12-inch at 60x. North is down and east is to the right.
| Millennium
Star Atlas Vol II Chart 782
Sky Atlas 2000 Chart 13 Uranometria 2000 Vol I&II Chart 233 Herald-Bobroff Astroatlas B-06 C-40 |
