| Planetary
Nebula
aka The Red Planetary, PNG 215.2-24.2, PK 215-24.1, ARO 3 Integrated Visual Magnitude: 10.7 Magnitude of Central Star: 10.2 Apparent Diameter: 12" Distance: 5000 ly Mean Surface Brightness: 15.8 mag/arc-sec2 Minimum requirements to view: a 4-inch scope under dark skies |
This
planetary nebula is unique because some observers report it to appear red
in the eyepiece. Planetary nebulae typically appear green or blue
if they show any color at all. It has been suggested that the red
or pink color appears most obvious without a filter and under direct vision.
It has also been suggested that the color visibility depends on the conditions
as well as the eye of the observer. The red hue may be most visible
at the outer edges.
The image on the right was obtained with the Hubble Space Telescope. Note how the reddish color is concentrated near the outer edge. In the eyepiece, this edge isn't nearly as obvious. Also note the intricate detail. This texture gives the nebula a unique appearance in the eyepiece that is rather indescribable. IC 418 is quite small, so make sure to use as much magnification as the conditions will permit.
After viewing it in my 6-inch, I wrote in my log, "Surprisingly high surface brightness. Small, slightly elongated disk. Obvious at 135X." It turned out to be a very nice little object, even for a six inch scope. The trick is to use as much magnification as the conditions will permit to see this nice little oval.
I later observed IC 418 in my 18-inch f/4.5. Here are my brief notes from my first encounter:
Cool! Small, bright. Bright central star. Oval. Gave impression of intense color -- only I could not tell what color it was!
This is the view in a 6" telescope at 50x. North is down and east is right. SkyTools eyepiece chart.
More recently I attempted to see the red hue in my 18-inch. At lower magnification (94x - 166x) I was struck mostly by the blue color of the central star. Higher magnification (430x) gave a much better view of the surrounding nebulosity. As I had my first look I twice had the distinct impression of a red or pink tinge, but this impression went away with time. I spent about 30 minutes looking. I used various eye positions for averted vision and looked at the nebula directly. There was a vague impression of color, particularly near the outer edge, but as last year I could not pin down what the color was.
What actually intrigued
me most was the impression of "texture" in the nebula. It seemed
smooth, yet somehow at the same time "lacy." I couldn't figure out
how to better describe the impression. Then I saw the HST image for
the first time! Now, I'm not saying that I could observe the intricate
detail directly, but its presence was surely "felt" at the eyepiece.
| Millennium
Star Atlas Vol I Chart 302
Sky Atlas 2000 Chart 11 Uranometria 2000 Vol II Chart 270 |
