Close Up of Comet 17/P Holmes 25 Oct 2007

Comet Hyakatake had a "bow-shock" of concentric rings on it's sunward side. Easily visible in an 8" SCT.

Probably caused by a rotating spraying geyser on it's surface.

This is probably a similar phenomenon.

Then again....this might be that alien spacecraft that followed Hale-Bopp around!

Them-thar pesky UFOs never seem to go away you know.

Peter.

Dave,
Are you referring to the black circle to the right of the core with a second black semi circle beyond it ?

Yes Dave, the two black arcs plus the brighter arc closer to the nucleus.

Dave, did you have any luck getting an animation together to see if the 'Catherine wheel' effect is operating here?

Frank,

Pea soup fog here tonight. saw the comet through a break in the clouds earlier and I'd estimate it about 1/2 way between Mirfak and Delta in brightness, maybe just a tad closer to Mirfak. Tomorrow night looks like a washout, so here's hoping it lasts till Sunday!

Took 20 x 3 second luminance images tonight to get this:



Then tried a H Alpha filter(as an experiment) at 40 x 10 seconds to get this:



Dave G the "shock wave" effects look far too strong to be a real feature and I've not seen anthing similar in any other images on the web. More likely a dust bunny popping up occassionally as the moon was covered/uncovered by cloud?

As for donuts or "dust bunnies" I'd agree though you never know Dave did say they appeared no matter where the comet was on the chip and that should rule out donuts.

My latest from tonight at 00:18UT 27/10/2007 is as follows: Canon 350D ISO100 30sec 3 composite, C102 SLT through horrible clouds and full moon.