Wow! you've done it again. By all means the ability to automatically
subtract darks and flat field the image would not only be handy but I think
would improve the astrometry. Quite often I have to go in and fix some hot
pixels that are near the object and when I do the centroid moves noticably.
I think that the most improvment would come in the photometry that Charon
uses to get a magnitude. I for one would be willing to pay for a copy of
Charon.

Bob Elliott
750 Fall Creek



At 15:30 2/28/00 -0500, you wrote:

>
>REQUEST FOR COMMENTS:
>
> (Those of you who don't do astrometry can safely ignore the rest of
>this e-mail.)
>
> I'm contemplating adding a new feature to Charon: a simple ability to
>use dark and flat images. Provide a dark image, and Charon could just
>subtract that from any image provided. (Provide _many_ dark images, and
>Charon would create a "median" dark image.)
>
> If you also provide a flat image, Charon would use that to flat-frame
>adjust any image provided. And again, given many flat images, it would
>make a "median" flat image and use that.
>
> Dark-subtraction would be almost trivial for me to do (in fact, I
>wrote most of the code to do it, in about five minutes, yesterday.)
>Flat-fielding is slightly trickier, but not too much so. I don't really
>want to rewrite MaximDL, but it seems to me that a few simple functions
>of this sort could lead to _much_ better astrometry. (Many of the images
>sent to me for testing look as if dark-subtraction alone would improve
>them immensely. Flat-fielding appears to be less important, and getting
>good flats is harder to do; still, those with vignetting or doing
>photometry would probably like this feature.)
>
> Before I get too enthusiastic about this, though, I'd like to get some
>comments from Charon users as to whether you would use something like this.
>
>-- Bill
>
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