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Old 20-12-2011, 06:21 PM
Ian Cooper
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Ian Cooper is offline
 
Join Date: Jan 2010
Location: Palmerston North, New Zealand
Posts: 126
Headless Comet

Hi Terry,

I've been trying to think of previous headless comets in history and you have nailed a significant pair of them, and from from the same family to boot!

Fortunately for us here on the lower North Island's west coast we are enjoying our first real purple patch of weather since September. A really foul spring, similar to 2006 which funnily enough culminated with McNaught's arrival. The forecast suggests that I will be up every morning from now until Christmas, and possibly longer.

I stll expect to see a good comet sitting above the twilight this week. This is my first Kreutz member. I was only 8 when Ikeya-Seki came through. My mate Noel saw that one. Noel actually mistook the tail for the Milkyway until he realized what it was! I wasn't into serious astronomy when White-Ortiz-Bolelli popped up briefly in 1970, so I missed on that one too.

Just re-read from Gary W. Kronk's book the references to those two Kreutz members. One thing that may still happen with this comet when it gets above the twilight, and the moon has lost all influence, could be a strong lengthening of the tail as seen from rural locations.

As an example of how faint the extreme ends of long comet tails are, according to the ship log of the Endeavour when Cook's crew observed Messier's best comet in September 1769, the tail was 70 degrees long. As soon as a thin morning crescent Moon rose the tail shrunk to only a third of its length!

Back in 2004 when we had the Duelling Comets in the sky, I advised would be astrophotographers to take a few ultra-widefield shots to pick up the true end of any possible tail. During the week that the two comets were at their best we had another spell of great weather. So good in fact that I had John Drummond of Gisborne travel the 400km to my place to get a good chance to capture the comets with his new DSLR. On May 19th, 2004, John captured the Ion tail stretching out to 45 degrees!

So once again I say, don't just concentrate on the obvious. Take some deep, wide-angle shots as well, even disgonalling the field along the line of the tail if need be!

Thanks for the discovery Terry. A great effort.

Cheers

Coops
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