Re: [guide-user] Another in favor of Charon!

Christian Ambros Jun 20, 2012


as I had to do some testing on my data anyway, I gave it a try comparing charon an on the same machine, charon in a dosbox... The results are not compareable. charon took more than 1 hour and was not able to get me any astrometry data from the same field as did within 12 seconds.

What I did was patching in a 1024x1024 fits image containing 0.502 arcsec/pix with a limiting magnitude of 27 and a field of view of 8.50483 x 8.5163 arcminutes. Simplexy found 1434 starlike sources.
I don't now why charon faild doing anything and why it did so long. 

Then I had a try on wifi-data and some mosaic images especially a testimage of the kidssurvey with 32x 35megapixel image. The wifi-images completed within 19 seconds, the mosaic in 22 and even the kids image took less than 37 seconds.

So I don't agree with you that astrometry takes hours to complete. 12 seconds is far from hours for a single image.

So I once again agree with Bill on his opinion that there are better ways to get the job done. does some other tricks, too. For example it sets the wcs coordinates right and updates the fits header in such a way that theses images could be included as real sky images guide.

At last, comparing the handling of astrometry command line and charon, it's much easier to use than charon because solve-field --overwrite --scale-units arcsecperpix --scale-low xx --scale-high yy --no-fits2fits image name.ext can't be beaten. As you can see I didn't provide it with further info than the image's pixel scale with isn't necessary at all.

I'm using the largest resolution with astrometry-0.38 and in parallel mode on a core2duo 2.1Ghz/4GB ram laptop (4 years old) running Linux Mint Debian. So nothing particular fast or special.

The test data were images of 2000AC229 taken at Skinakas Observatory, Crete in 2001, RXCJ1825.3+3026 (galaxy cluster from the REFLEX and NORAS sample in the zone of advoidance) taken at several observing sites from Skinakas to La Silla and Calar Alto.

I can provide some of this data for testing as well as mosaic and wifi data can be downloaded form eso archives.

Still charon is an amazing peace of software an it did it's purpose years ago quite well, but things had changed over the years.

"A little learning never caused anyone's head to explode!"

"Ein wenig Lernen hat noch niemandens Kopf zum Explodieren gebracht!"

> Von: grantcblair <g.blair@...>
>Gesendet: 14:02 Dienstag, 19.Juni 2012
>Betreff: [guide-user] Another in favor of Charon!

>Hi Bill,
>I'm not often vocal, but I have to agree with Dr Clay and the others in support of Charon - it's lean and it does an absolutely fantastic job (better than PinPoint and, in my opinion). If you can give it an approximate starting position and a pretty good idea of the image scale (which everybody should know after their first image with a particular setup), it beats everything else hands-down.
>When I'm imaging, I really don't want to have to refine my inputs a dozen or more times to get PinPoint to spit out a valid answer. And I really don't want to wait HOURS (literally) for to _sometimes_ provide an answer. Charon "just works". And as an physics/software geek for over 20 years, "just works" is about the highest compliment I could give anyone's software. Charon (and Guide, of course) are up there with BackyardEOS in that respect - peerless.
>Of course, I still use WindowsXP on my observatory computer for much the same reason Dr Clay does. If it ain't broke, don't fix it...
>Thank you!
>Grant in NJ

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