Could I have a few opinions on what date and time Chiron is due to enter the tropical sign of Pisces? Earlier comparisons seem to suggest that computor programs vary or disagree on ingresses and may limit the usefulness of such attempted work.

Astrocalc v5,602 - April 2
Astrocalc v7,5(old version) - April 3
American Ephemeris - April 20 !!

It could be a good idea to look at an oddball like Chiron both because it isn't considered to be an astrological heavyweight (and not treading on anyones toes!!) and it icould also be interesting due to the potential perturbations of its orbit.

Astrodienst has 20 April,

PS I looked at their swiss ephemeris and it has 20th and 00 UT 29 Aqu 59 and 21st as 00Pis 02 so again sometime on the 20th as far as they are concerned.

granny

I think it was Lee Lehman who mentioned to me that the American Ephemeris hasn't been updated in 20 years or so, which is a little spooky.

20 April 6:32:22 am GMT per Janus. My ephemeris is Chiron-free.

Astrolog 5.41g uses the Swiss Ephemerides from astro.com.

The dates given are as follows, all Greenwich mean time:

Zodiacal
(Tue) 4/20/2010 6:31 Chiron (Aqu) --> Pisces

Right Ascension
(Tue) 4/20/2010 19:30 Chiron (Aqu) --> Pisces

Heliocentric
(Mon) 12/20/2010 13:20 Chiron (Aqu) --> Pisces

Interesting question. Thanks for bringing it up.

Jane Axtell

As the new owner and developer of Astrocalc I would like to try adding come clarity to this. The main reason for variations, at least in regards of Astrocalc, is that it uses a calculated ephemeris rather than the Swiss ephemeris some other programs use, which contain fixed data stored in a table digital format.

The original reason for this is space and origins back to the Dos days, and while other programs usually came on loads of floppies Astrocalc came on just one single floppy, later 3 floppies as the Atlas became available.

So which is best? Well they both have their strengths and weaknesses. To visualize and simplify it a bit I will from now on call them Dynamic and Static ephemeris instead as it?s more descriptive of their nature.

As already been said a Dynamic Ephemeris doesn't take up any storage space while Static needs lot of space, I am not sure though how much space the Swiss Ephemeris of today use, any? It should be noted here that storage space generally isn't an issue today but might be so in some circumstances.

I am not absolutely sure of this but it ought to be so that Dynamic is faster as it doesn't need to read data from disc media as with Static and of course before the data can be read it has to be looked up in the table, which also takes time. As an example it can be very "expensive" to use a Static ephemerid in a Network solution.

Static Ephemeris is (more or less I think) based on observed values which generally give it a higher accuracy, without implying the accuracy of a Dynamic ephemeris has to be bad. The Dynamic is also based on observed values but uses it more as a reference transformed into a complex calculation algorithm.

In most cases we are talking about 1 or a few seconds of an arc minute. As in the Saturn Ingress example mentioned earlier it's 7'', most charts you see doesn't bother with arc seconds and I don't know if they even can show them - as I don't bother to find out I think this is more an issue with the outer planets than the inner, but it might be fair to say that a Static ephemeris is better suited to use for Ingresses. I still have to do some investigations here though as it?s something I haven?t thought of before because most of the time charts are calculated and drawn based on a timed event taken place on Earth and not outside of it.

There is another issue here though, as time goes on we learn more about the space this ball is bumping around in and old observations may prove to be slightly wrong, in such case Static is just Static and everything has to be adjusted, while in a Dynamic ephemeris it may be enough to adjust a small value in your settings or if worse a small adjustment to the algorithm may be needed.

Another disadvantage of static is the limitation of its scope in time, I am not sure what that is for the Swiss but Astrocalc's Dynamic ephemeris can make calculations, with kept accuracy in a scope over 5000 years and further although it has to give up its claim for accuracy then. I don?t know exactly how e.g. the Swiss deals with the future as it?s still to be observed, so it has to be calculated as well.

There might be more to it I can't come to think of now. I also want to stress that the calculation routines in Astrocalc wasn't written by me but by Colin Miles which also includes work doneby others but mainly by John Dice. Also I don't know to what extent the Swiss Ephemeris is maintained and how it is with software using it as they need to update to any new release to benefit from it.

I think I can say the ephemeris in Astrocalc is of very high quality and deliver high accuracy and in parity with the Swish in most cases, although maybe not in all. But as said before, it mostly comes down to a second or a few of an arc minute, something most doesn't bother to look at when working with timed events.

However, I don?t exclude the possibility that time has edged them a bit, although just a bit but not enough push them off target. As astrological and astronomical calculations also involve a lot of floating point values, the CPU?s in our computers may also cause small variations as some machine code may be dealt slightly differently than others and by various CPU?s but we are still talking about variations in the end of a 14 digit decimal. I have seen such variations in running the same code in older and newer programming environments. But again, we are talking of double precision values here with up to 14 decimals so in the end it will hardly make any difference.

It's interesting though Andrew when you mention the difference between the old Dos version of Astrocalc and Colin's last version (5.6), I must look into this as maybe a mistake has been done somewhere along the road, or something was adjusted in the calculations, for good reasons I assume. Don't be mistaken about it, Colin Miles is a very serious man but just as anybody he's also able to make mistakes. As for Chiron he says this in the Astrocalc help file:

This is a very small comet which astrologers got very excited about when it was first discovered. This was largely because the media misreported as being the 10th planet. There are currently at least 5 different symbols used to describe it and very many more meanings ascribed to it. Some meanings include teaching, healing, maverick, difficult births, easy births, the symbol of Access (Handicapped symbol used in cars). The orbit of Chiron is chaotic and unstable so that it's positions cannot be determined with great accuracy.

Various ephemerides have been produced each claiming greater accuracy than the last. Some of the latest have, unfortunately, not taken into account the closeness of Saturn in 1966 so that latest 1966 values are now less accurate than they used to be! Chiron orbits between Saturn and Uranus and at least 13 similar bodies have been discovered in the regions of Saturn, Uranus, Neptune and beyond Pluto. The August 94 Astronomer magazine talks about 'millions of Chirons'.

Well I guess it's quite clear that Colin Miles isn't any great fan of Chiron but I am pretty sure it hasn't clouded his judgment when he implemented the ephemeris algorithm for Chiron and I know he has devoted many hours to the subject of Astronomy. To anyone who wonder, Colin Miles is the founder of the Astrocalc software back in 1982, hence it?s one of the astrology programs that been around longest in time.

At the end of the day I must admit that I cannot say for sure which Chiron Ingress in Pisces are correct as I haven't got quite that far yet in my astronomy studies and I don't know what is the source of the other value, I mean what source Swiss uses. I will try to make some research though.

Thank you for the expaination, Joakim.

I enjoy a free download of Winstars (astronomy). Sometimes I wish there was a button that would convert all the positions into zodiacal longitude.

Andrew Bevan wrote:Sometimes I wish there was a button that would convert all the positions into zodiacal longitude.

Not a button but perhaps of some help,
http://www.antonblog.net/tools/
http://www.antonblog.net/tool/coordinates.html

Or the calculator, in case the internet is off the air .
http://en.wikipedia.org/wiki/Ecliptic_c ... oordinates

I can only say that I would be helpless without the knowledge of Joakrim Schramm, Colin Miles, Terry Dwyer and the like. Thank you for maintaining the bridge between modern astrology and science!

Deb wrote:HI Joakim - thanks for the update. Please add your link too so readers can go straight to your site.

Best wishes
Deb

Deb, thanks for confirming this to be ok, I have put it in my sig so I can forget about it