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3 Morning Comets on 10/5

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#1 Wes Stone

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Posted 05 October 2013 - 04:25 PM

I left my 10" Dob on the deck to cool off overnight. I got up before 3am to check out 3 comets in the morning sky. The air was cold, but transparency was pretty good (limiting magnitude probably around 6.8 overhead).

My first target was 2P/Encke in Lynx. I previously saw this comet in 1994 and 2003. Once I starhopped to it at 47x, Encke was an obvious fuzzball at all magnifications. The surrounding star field was very pretty with a couple of bright star chains. The comet's eastward motion was obvious within a few minutes.

Encke showed a coma about 5' in diameter, round or diffusely elongated a bit to the NE. A small, fairly weak central condensation was displaced to the west of the coma's center. A narrowband filter (Orion UltraBlock) made the outer coma better-defined, although it did not reveal any additional detail or extent. I estimated the coma magnitude as 10.0. Sketch: http://skytour.homes...es/2P131005.jpg

C/2013 R1 (Lovejoy) was a quick starhop from Beta Monocerotis, although I noticed my Telrad was beginning to frost up. Lovejoy was also an easy object from the get-go. Its coma was smaller but more condensed than Encke's. A 12th-magnitude star was embedded in the coma, and the comet's motion brought the coma's center ever closer to the star. My impression was of a triangular central condensation with a stellar nucleus. Overall, the coma was about 2' x 2.5' and elongated in PA 270. I didn't try a magnitude estimate due to interference from the star. Sketch: http://skytour.homes...13R1-131005.jpg

Finally, there was (will it or won't it disintegrate) C/2012 S1 (ISON). ISON was buried in the bright zodiacal light near Mars, and the sky background was disappointingly bright. Seeing wasn't good at 20-30 degrees altitude, either, as Mars was twinkling to the naked eye. Nevertheless, ISON was an obvious elongated smudge at 47x, and much easier than when I last observed it on September 11th. I switched to 165x for a sketch, but had persistent problems with eyepiece fogging in the 24 degree (F) air. ISON had an inner coma about 1' in diameter, with a possible outer envelope about double this. The coma appeared more condensed at low power, but with no stellar nucleus. A faint tail extended for 3.5' in PA 295. I estimated ISON's magnitude as 11.1, compared to 11.8 back on September 11th. Sketch: http://skytour.homes...12S1-131005.jpg

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Wes Stone
Chiloquin, OR
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#2 Kevdog

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Posted 05 October 2013 - 07:17 PM

How dark are your skies? I tried for both Enke and Ison last night and the only thing I saw was a slightly fuzzy smudge with no apparent coma. I'm in a yellow zone with an 18" and I thought I'd see more.

#3 Wes Stone

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Posted 05 October 2013 - 08:35 PM

How dark are your skies? I tried for both Enke and Ison last night and the only thing I saw was a slightly fuzzy smudge with no apparent coma. I'm in a yellow zone with an 18" and I thought I'd see more.


My skies are quite dark (blue zone, limiting magnitude 6.8). Both comets were fuzzy smudges to me as well (if you see fuzz, then by definition you're seeing a coma). The difference is the extent of the fuzz. Encke's diameter of 5 arcminutes isn't that large, but it was actually pretty impressive considering the dinky comets I've been looking at. I think it's possible that with a large scope in not-so-dark skies you might see only the brighter inner 1 arcminute or so of coma on both Encke and ISON. If you've got a nebula filter (broadband or narrowband), you might try it on Encke.

At this point, none of the comets are showing a lot of detail in a 10", just some tantalizing hints.

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Wes Stone
Chiloquin, OR
http://skytour.homestead.com

#4 elmiko

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Posted 06 October 2013 - 12:01 AM

I imaged Ison from the All Az star party on Saturday morning around 0400. Try to attach pic. The comet is the faint smudge right of center, with the tail pointing upward.

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