Comet Holmes 17/P

David Kingsley

But the comet was still naked eye, and an amazing thing to look at in a scope. Even my wife and sons thought it was cool looking when I called them out to the backyard to take a look. Alex's sketch is outstanding, and captures the "sulfur-colored planetary" appearance described by Bill Cone. The small bright fan from the nearly stellar core was obvious even through thin clouds.

I initially missed the faint glow around the sulfur colored disk that was mentioned by Matthew Marcus. However, when I went out again after midnight, the high thin clouds were briefly gone around the comet and I saw several additional features. There is definitely a much fainter round circular glow around the bright central disk. I played around with the bulls-eye pattern of a Celestron Microguide eyepiece to estimate relative sizes. The bright central disc almost exactly filled one of the circles in the bulls-eye pattern of this reticle eyepiece. And the fainter outer glow filled the larger bulls-eye circle that has twice the diameter of the bright inner disc. The bulls-eye rings and linear scale should provide a convenient way of telling whether the inner disc and outer halo change much in size or symmetry over the next several days.

It also looked like the bright inner yellow disc has a ring around its outer edge that is clearly brighter than the central region of the disc. Very much like an annular planetary seen nearly face on, though much more subtle than M57.

This image posted by Teri Smoot on TAC-SAC gives some idea of the relative brightness and size of the bright inner disc and dim outer halo. And if you look closely, you can also see the slightly "ring nebula" like annular appearance to the bright inner disc (though no sign of the bright fan shaped core within the inner disc, at least on my monitor).

http://home.earthlink.net/~montanacg/index.html

The year started with McNaught. And now we get the completely unexpected spectacle of another amazing comet, brightening almost a million fold in two days and visible to the naked eye even with a full moon outside! I have never seen a comet with the color and planetary nebula appearance of this one. Can't wait to see what happens to it next.

--David Kingsley