| The
Planetary Nebula Abell 12 |
Planetary
Nebula
aka
PNG 198.6-06.3, PK 198-06.1, Abell 12, ARO 220
RA:
06h02m21.4s Dec: +09°39'07" (Orion)
Integrated
Visual Magnitude: 13.9
Angular
Diameter: 37"
Mean
Surface Brightness: 21.5 Mag/arc-secē
Distance
6900 ly
Minimum
requirements to detect: 8-inch and OIII filter under suburban
skies |
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Abell 12 is an interesting
planetary nebula that is a challenge to observe due to its proximity
to the 4th magnitude star Mu Ori. Mu ori is the next
star up the chain to the north from Betelgeuse, so finding the field
is quite easy. Making out the nebula in the glare of the star
is something altogether different. The trick to finding Abell
12 is to use an OIII filter. The UHC filter helps some, but it
takes the OIII to really bring it out. I had tried several
times and failed to see this planetary in my 18-inch without a
filter. When I finally inserted an OIII it popped right into
view!  To
me Abell 12 looked like a blob within the bright halo of Mu Ori.
The nebula appeared to almost touch the star. I thought I
detected a ring, or donut shape. The image above confirms the
ring and is quite intriguing. The bright object with the blue
halo is Mu Ori. The smaller object to the left (east) is the
planetary. The edge of the nebula forms a bright, thin,
regular ring, that doesn't quite close onto itself. Quite odd!
Dave Aucoin wrote that he "observed elongated structure much
like a lenticular in shape" in a 13.1" Dob.
The field in an 6-inch f/8 at
50x. North is down and east is to the right.
|
Millennium
Star Atlas Vol I Chart 204
Sky
Atlas 2000 Chart 11
Uranometria
2000 Vol I Chart 181
Herald-Bobroff
Astroatlas B-05 C-40 |
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