Re: Comet thought experiment.

From: GD (alfa_at_melb.something.au)
Date: 01/13/05 

Date: 13 Jan 2005 18:03:01 +1050

Chris L Peterson <clp@alumni.caltech.edu> wrote in
news:4mdau05jqisu6go7anoqbu4niclhq4d3ff@4ax.com:

>>What I had in mind was taking a few CCD images of the same patch of
>>sky, each image taken through a different filter (UHC, Swan Band
>>etc...). Then a bit of software would look though the images and
>>display a view based on how similar the intensities of each pixel in
>>those images represented the intensities expected by a comet.
>
> This could work in some cases, but it probably wouldn't be as
> efficient as you'd like. First of all, to get good spectral resolution
> you would need to use fairly narrowband filters, which means you would
> be throwing away a lot of light and your individual exposures would
> have to be quite long. Second, it is very easy to automate a search
> for movement. It is only when the comet is still very far out that the
> movement is small and harder to detect, but when it is far out it also
> isn't showing much secondary emission from solar radiation, and the
> distinct spectrum you are looking for isn't there.

Thats cool. These things were issues that I'd already though of, but
wasnt sure if anybody has actually *tried it* yet. :)

So... if anybody reading this needs a reason to go outside tonight, I'd
love it if somebody could take some images of any recently discovered
comet, using perhaps 3 different narrowband filters (one for each image),
and email them to me. I'd then throw a bit of software at them to see
if anything about the comet spectrum stood out as distinctive compared to
the background stars (or not).

cheers...

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