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Old 15-02-2013, 11:53 PM
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mental4astro (Alexander)

mental4astro is offline
Join Date: Jun 2008
Location: sydney, australia
Posts: 4,797
Thanks Orestis. Colour? I think I could make out a faint hint of bluey-green. Would need a dark site to confirm.

Tonight's close encounter of Comet Lemmon and 47 Tuc was an opportunity that couldn't go by unviewed. I'm sure that the photophiles will be busy tonight too.

I went a bit stir crazy tonight too. I set up two scopes tonight knowing that with a larger aperture the duo wouldn't be possible to view at the same time. So I set up my 8" f/4 dob and my 80mm f/5 refractor.

The first sketch is with the 8" at 80X using a 10m XW. Not only was the comet brighter than I saw last week, but its tail was also easier to tease out. It's a long thin ribbon that extends out from the nucleus, the coma and hydrogen cloud giving the comet a big 'head'.


I was in for a double surprise with the 80mm refractor. I used a 36mm Aspheric Hyperion here as it gives me a full 6degree TFOV - massive! Here, the advantage of a small aperture over a large one in a heavily light polluted enviroment became evident. A large aperture makes the background sky glow too intense in urban areas, making low power a difficult proposition. Yet, a smaller aperture isn't affected the same way, making low power more practical. The result here was that at 11X I could also make out the tail.

The second surprise was that just squeezing into the FOV is the smaller globular cluster NGC 362. Sadly, the SMC that would be in the FOV is just overwhelmed by the Sky Glow, even in a small scope.

In the second sketch, Lemmon is at the lower right, 47 Tuc is in the centre, and 362 is in the top left.

Both sketches took about 1/2 hr to complete.

Attached Thumbnails
Click for full-size image (Comet Lemmon 15-2-13, 80X.jpg)
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Click for full-size image (Comet Lemmon 15-2-13, 11X expanded view.jpg)
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