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Ephemeris question

Posted: Sat Feb 24, 2007 1:21 pm
by wendyh
I've been using Astrodienst's online charting facilities for a number of years. Now I've got to the point where I need my own software. One of the reasons why I downloaded and purchased Kairon was because it uses the same ephemeris.

However I notice that my charts in Kairon are showing differences of 1 arc minute in many planetary/point placements compared to the charts I drew up in Astrodienst's software.

Why is this?

Posted: Mon Feb 26, 2007 11:03 pm
by George Orwell

I can't answer your question directly. But I do have astronomy software (starry night) which is used to control telescopes - so the positions on that must be pretty accurate, otherwise it wouldn't last very long.

So, if it is useful to you, by all means give me some planets, times and geographic locations that you are using, and I'll check them out in Starry Night, then at least you will know which of the results that you are getting is the more accurate!


Posted: Mon Feb 26, 2007 11:22 pm
by wendyh
Thanks for the offer, but I'm not so much interested in the absolute accuracy (1 arc minute is mostly neither here nor there in the general scheme of things), but in why there is a difference between Astrodienst and Kairon when both programs are using the same ephemeris.


Posted: Mon Mar 05, 2007 12:36 am
by mehemptah
differences in calculation come only from differences in location and time. how to properly enter all the data is also described in the online tutorial :-)

Posted: Mon Mar 05, 2007 1:50 am
by wendyh
As I said in my other posts, I went through the online tutorial several times over, particularly the bit on how to add locations to the custom atlas, and only posted here because what the program was doing, (or what I was doing with it according to my reading of the tutorial), didn't seem quite right or left me with some questions.

The question about the 1 arcminute discrepancy is based on having entered into Kairon identical lat/long location data to what is used in Astrodienst's software -- or at least what is displayed on a printed Astrodienst chart. If the lat/long displayed on an Astrodienst chart has been rounded up from more precise underlying data, then that might explain the difference.

Posted: Mon Mar 12, 2007 6:30 pm
by mehemptah