Skyscript Astrology Forum

Perhaps the latest research on ancient horoscope calculation has been done by Dimityr Kojuharov. Below are two of his posts from the ACT Astrology Forum. Dimityir does admit that some of his conclusions may be in error. This suggestion refers to the possible/probable dates when sidereal chart calculation changed to tropical. (As per his research.)
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Re: Research Studies: Tropical vs. Sidereal & Related

by Dimityr Kojuharov on Mon Oct 17, 2011 11:26 pm
The main problem in the study of ancient charts(for nativities and events) is incorrect methodology which was used from the previous scholars.
Most of ancient charts give only the longitudes of planets.Data for the month and the year of the chart most often are missing.First O.Neugebauer and later D.Pingree and others used incorrect methodology for recomputation of the charts:
1.They used MODERN, not ANCIENT astronomical tables for these calculations - what is a wrong approach.
2.They used Tuckerman's tables[1962 and 1964] which have systematical errors-the error is in all longitudes of Mars.These errors in Mars are avoided in corrected tables of Houlden and Stevenson[1986]
3.They don't test in which zodiac are the Greek horoscopes after Ptolemy-in the tropical or in the sidereal one. Neugebauer just assumed that after Ptolemy and Theon Alexandrinus all Greek horoscopes are calculated in the tropical zodiac which is a wrong thesis.

Only in the researches of one modern scholar, Alexander Jones, we can see a right approach:
-first he gives the longitudes from the original text
-then he used Handy tables from Theon's book for recalculations of the charts together with Theon's instructions from his Small Commentaries to Handy tables
-finally he gives modern computations for these charts

This is the correct way to reconstruct the ancient astrological charts.
Dimityr Kojuharov

by Dimityr Kojuharov on Mon Oct 17, 2011 11:43 pm
What we can see as a result for the nativities and events charts (not for solar return charts)?
Below are the results of my preliminary study of the scientific papers which deal with old nativities and events charts.This problem-with which zodiac are worked the ancient astrologers needs new comprehensive and serious study involving recalculation of all survived charts with the methodology described above. Errors or erroneous conclusions are possible and are not excluded in this my survey.

1.Hellenistic period
-all charts from Hellenistic period are calculated in the sidereal zodiac, including charts from the late Antiquity or many centuries after Ptolemy
-only occasionally in the late Antiquity we can see charts calculated in the tropical zodiac-chart of Proclus(for 412 A.D.) and a anonymous chart from Oxyrhynchus(for 508 A.D.)

2.Sassanian(Persian) period
-all Sassanian astrologers used sidereal zodiac and give the longitudes in this zodiac

3.Arabic period
-first generation of astrologers, which are in most cases Persians, calculated charts in sidereal zodiac.These calculations are based on Shah's zij from Sassanian period and other zijes from Indian origin which contain sidereal parameters
-later generations of Arabic astrologers after the translation of Ptolemy's Almagest, Theon's Handy tables and Tetrabiblos too, started to calculate the charts in the tropical zodiac
-only in Maghreb and al-Andalus regions to the middle of XIV Century we can see continuation of this tradition-calculation of longitudes in sidereal zodiac

3.European period
-in which zodiac are calculated charts in the first centuries after the entry of astrology in Europe is difficult to say at the moment, but the first European tables-Toledan tables(1080) and Alphonsine tables(1240) are sidereal .After Prutenic tables(1551) and Rudolphine tables(1627) we can say with certainty that astrologers calculated charts with tropical longitudes.
Dimityr Kojuharov

Theresa, I would like to know more about Kojuharov?s research ? has he published? His work sounds very interesting, although without demonstration of data and argument it?s hard to know what to do with a comment like ?all charts from Hellenistic period are calculated in the sidereal zodiac, including charts from the late Antiquity or many centuries after Ptolemy?, especially where he admits his conclusions may be erroneous. I do agree with what he?s saying though about the problem of reconstituting ancient charts according to modern computations. That?s why I hesitate myself. For example, I can check star positions against those listed in Ptolemy?s Almagest, but how would I even know that the position was that listed by Ptolemy himself, rather than an updated position in a later edition of the work? We are in need of researchers like him who will not only do this work, but also demonstrate it in ways that other researchers can follow it clearly. One point that struck me from his post is how much the calculation preferences probably fell down to convenience and the availability of tables ? I wouldn?t be surprised if far fewer astrologers deliberated on the philosophical and astronomical principles involved than we assume would do that.

With regard to Valens and ancient works, one point that bothers me is that the discussion of ancient zodiacs gets blighted by confusion when methods of division are exclusively defined as either sidereal or tropical, without clear explanation of what is meant by those terms. Any use of an equally divided zodiac which is centred upon the ecliptic has ceased to be fundamentally ?sidereal? as it was in the ancient systems that preceded identification of the equinoxes and solstices. The older planetary measurements were properly sidereal, drawn from reference stars and (at least by the Babylonians) the constellations that lay in the path of the Moon. Since the Moon is never more than about 5 degrees off the ecliptic, and the rest of the visible planets remain close to it (because they are all revolving around the Sun on a similar planet of orbit) this draws attention to the constellations that are close to the ecliptic ? hence we get similarity in where the focus lies but conceptually it is an entirely different scheme from that based on zodiac measurement along the ecliptic. The latter generates a radically altered astronomical/astrological mechanism which significantly advanced knowledge of planetary cycles, but could not be introduced until the knowledge of the Sun?s turning points had first been astronomically established. Hence when modern siderealists talk about sidereal astrology being the original system of astrology with a very ancient legacy they are correct, but it should also be made clearer that what constituted that very ancient sidereal astrology bears little relevance to any modern use of an ecliptic based zodiac scheme ? or to anything Hellenistic astrologers such as Valens were using.

Martin, you write ?Of course, the Babylonians did not know about precession, so to them the zodiac was simultaneously 'sidereal' and 'tropical'?. I'm not so sure that the Babylonians were ignorant of precession. Greek astronomical knowledge before Thales was rudimentary compared with that of the Babylonians and many scholars hold the view that Hipparchus made a rediscovery (or a Greek discovery) of something that was pre-existing knowledge to more ancient civilizations. I not certain of anything myself but being interested in the development of ancient astronomical and astrological principles I?ve come to consider it more likely than not that the Babylonians were aware of precession. There are many reasons for this ? partly because one of their major drives for astronomical development was calendar precision; partly because their astronomical observations were strongly focussed on horizon events, which is where it needs to be to monitor the seasonal changes of the Sun?s cycle; partly because the events that interested them most (eclipses and lunations) cannot be advanced to the extent they were without reliable knowledge of equinoxes and solstices, and partly because we have the historical reports of the equinox slipping backwards, which identify it being marked at the 15th, 12th, 10h and 8th degree (after which the controversy of whether it should be fixed at the first degree arises). The sophistication of Babylonian astronomy and mathematics is often overlooked, and it seems illogical to me that a society which is known for creating the most exhaustive record of daily celestial observations was not also capable of applying their known astronomical/mathematical expertise to analyse the data and note the same obvious drift of position over time as Hipparchus did. But here I am talking about Babylonian astrologers who were also acting as astronomers and had to understand astronomical matters. You are right to question whether an astrologer in subsequent times would be so astronomically aware.

For the record, my own belief is that the zodiac was introduced as a mathematical arrangement around the 8th century BC, with the equinoxes and solstices purposely aligned to the centre of the idealised constellations that lay behind them. Hence I assume that many ancient associations of Aries develop out of the fact that it simply held the equinox, and that the issue of whether Aries should continue to act as the initiating sign didn?t create a huge problem until Ptolemy?s time, a thousand years later, when the equinox was moving out of Aries. This makes sense of older references carried forward in Hellenistic works, which describe the equinoxes, solstices and antiscia connections as if they are aligned with the centres, rather than the beginnings of the signs. Plus we have some telling phrases in works such as Manilius where Virgo is described as a ?double sign? with the explanation that ?the duality in her appearance is not the reason; for at the middle of the Virgin summer on one side ceases and autumn on the other begins? (2.175). The Astronomica was clearly out of date by the time that the Roman poet took on the job of versifying information that we know to be drawn from older astronomical works.

My interest in the Valens quote on Aries is that I?d love to know whether the Greek text only allows a correct interpretation which describes the thunder and hail ?up to? the equinox, or whether it could be interpreted as ?around? the equinox. We see from Ptolemy that association with the equinox marks the whole sign out as characterised by thunder and hail, but of course at that time the whole sign was characterised by the fact that the equinox fell at its beginning. I like the idea that it is the equinox itself that has this association ? it?s the place where something astronomically dramatic occurs so as an astrologer I want this to see this reflected in dramatic effects!

Well, Deb, we are neither of us assyriologists, so I won't argue with your views on Babylonian astrology/astral divination; I will only say that as far as I know they are not mainstream.

I do question this line of argument, though:

Any use of an equally divided zodiac which is centred upon the ecliptic has ceased to be fundamentally ?sidereal? as it was in the ancient systems that preceded identification of the equinoxes and solstices.

There is nothing intrinsically sidereal or tropical about the ecliptic. It is a great circle defined by the Sun's apparent motion against the background of the fixed stars (sidereal) and crossing the celestial equator at the equinoctial points (tropical). Astrology in no way ceases to be fundamentally sidereal because it recognizes the ecliptic.

My interest in the Valens quote on Aries is that I?d love to know whether the Greek text only allows a correct interpretation which describes the thunder and hail ?up to? the equinox, or whether it could be interpreted as ?around? the equinox.

The Greek word used is ?????, which means 'as far as, up to, until'.

Something that might be worth mentioning here is that in Valens' own chart, or at least the chart that Pingree inferred to be Valens' chart, Saturn is right on the cusp of Gemini and Cancer. When Valens mentions the chart a few times he consistently says that Saturn was in Cancer. When the chart is calculated using tropical values Saturn ends up at 29?14 Gemini. It is only the sidereal values that put it in Cancer. Fagan-Allen puts it at 0?38 Cancer, and Lahiri puts it at 1?31. Obviously Valens' tables aren't as precise as our own, so one might be able to chalk this up to a calculation error, but the point still stands that for one of his own chart placements Valens was basically using a sidereal value, either deliberately or inadvertently.

Aside from that, Jones recently published an important paper in Ptolemy in Perspective where he tabulates all of the existing horoscopes and basically points out that the values were largely sidereal during the early Hellenistic tradition, and it wasn't until a few centuries after Ptolemy that a distinct transition took place where the charts became tropical. It seems like this is more or less the same conclusion that Dimityr Kojuharov came to in the thread that Therese quoted earlier, although in Jones' case his paper has been published, so it is open for review.

Well Martin I am presenting my own views here and try to make it clear when I am speculating - all we can do in this sort of informal exchange of ideas. But note I said "Any use of an equally divided zodiac which is centred upon the ecliptic has ceased to be fundamentally ?sidereal? as it was in the ancient systems that preceded identification of the equinoxes and solstices". If you drop off the latter part of my sentence it loses its relevance to the point I was making.

Thanks for responding to my request for clarification on the Greek word. Do you have the Greek text for all the bit that Schmidt has translated as "Aries is watery in nature, full of thunder, hail. More particularly, the first parts up to the equipartite [place] are full of thunderstorms, hail wind and destruction; the middle parts up to the 15th degree are temperate". If so, would you share? It does seem odd that Gehrz translates it so differently. Are there alternate manuscripts giving different versions of the text as there is with Ptolemy's work? Maybe I should write and ask Gerhz if she would stand by that translation after reconsideration (it could be a simple mistake - I'm sure all translators make them).

Our posts crossed Chris. Thanks for reminding me, I have that - but it's also significant that Jones summarises that "the astrologers of Ptolemy's period did not distinguish between the tropical and sidereal year, and used a frame of reference that was assumed to be tropical but in fact was approximately sidereal. Ptolemy's tables assume a tropical frame while attributing a precessional motion to the fixed stars. Papyri show that for two centuries after his time, Ptolemy's tables were commonly used only together with a correction that brought computed positions into a standardization of the prevalent frame of reference". (p.xiii)

So it may be the case that even the computations that appear to support the use of a fixed zodiac are not down to the astrologer purposely adopting this perspective in principle - just the result of their trust in the tables they were working with. At that time it hardly mattered, but according to Jones they assumed that their frame of reference was the tropical one. It seems logical to me that the Greek astrologers at least would be doing that, since fixing the 0 Aries point at the equinox is so clearly described by Geminos as being the normal convention of the Greeks.

Hello

Martin Gansten wrote:There is nothing intrinsically sidereal or tropical about the ecliptic.

I sort of agree with this part.

I'm afraid I don't agree with the next part...

Martin Gansten wrote:It is a great circle defined by the Sun's apparent motion against the background of the fixed stars (sidereal) and crossing the celestial equator at the equinoctial points (tropical).

I would say 'sky'. The background is arguably simply the sky itself, first and foremost. The fixed stars and/or the crossing and turning points can be used as reference points for seeing meaning, but there is no need to define the ecliptic in terms of either the stars or the crossing+turning points. The path of the Sun exists in and of itself, up there in the vault of the heavens.

I agree with the next part, but would add something....

Martin Gansten wrote:Astrology in no way ceases to be fundamentally sidereal because it recognizes the ecliptic.

Agreed, however nor does astrology necessarily become or exist as fundamentally sidereal by recognising, measuring and seeing meaning in the sun's path. They are able to be discriminated. The Babylonians were a clever bunch.

Regards

handn

Hello

Whether academics or 'amateurs', mainstream or fringe, unconscious assumptions can easily trip anyone up.

There is ample evidence that peoples long dead and buried had blazing clarity about many things which in later peopes' minds became foggy, and even amongst some became wholly lost.

I think it's problematical to point to dates and say 'precession wasn't known about before then' or 'they didn't distinguish between tropical zodiac and whatever sidereal-rooted system you wish to point to' and so on and so forth, based on texts alone. The fact is we don't know anything for certain (which is why it's so interesting as a topic of discussion).

What they wrote and what they did and what they knew about weren't necessarily all the same thing. This is stating the obvious and you all know it already, but I think it needs to be said as a reminder.

If something is simple, clear and obvious, then it's possible that it wouldn't need writing down in detail in great treatises. If something can easily be carried in the memory, or computed by one's mental 'ready reckoner', why waste a clay tablet on it? What is difficult for us could have been child's play for them, and vice versa.

There is no automatic linear progression of knowledge or skill or ability over centuries or millennia. The process of passing on and handing down is full of risks of mutation and loss, caused by various factors.

We live in an age when we can jot down any trivial nonsense that comes to mind, and so we do. They didn't.

We need to be careful what we assume, especially unconsciously.

My closing point is that academics can be as wrong as anybody else, as can mainstream opinions, and that whilst it is immature and stupid to refuse to deeply consider and deliberate over what the mainstream views are or what academics tell us, on the other hand we do not doff our caps automatically to mainstreamness, nor to academia. If we did, we wouldn't be doing astrology in the first place.

Regards

handn

Deb wrote:

I would like to know more about Kojuharov?s research ? has he published? His work sounds very interesting, although without demonstration of data and argument it?s hard to know what to do with a comment like ?all charts from Hellenistic period are calculated in the sidereal zodiac, including charts from the late Antiquity or many centuries after Ptolemy?...

I agree that we need more information. As for Kojuharov, I only know what he has posted on the ACT forum. Here is another small quote of his from ACT:
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by Dimityr Kojuharov on Tue Oct 18, 2011 11:13 am

Q: Can you give an internet reference for Alexander Jones?

Alexander Jones, Astronomical Papyri from Oxyrchynchus, volumes 1 and 2, Philadelphia, 1999

The most impressive statement of A. Jones is on the p.49 of his book, where he says that the Greek astrologers(after Ptolemy) used Ptolemy's tropical longitudes from Handy tables and then they used a special formula (Theon's rule) to convert these tropical longitudes into the sidereal. So the final result is a horoscope in a sidereal zodiac.
Dimityr Kojuharov
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...especially where he admits his conclusions may be erroneous.

The possible questioning of conclusions refers to exactly when and in what cultures zodiac calculations changed from the sidereal to the tropical. He is suggesting that further research could change what he's found so far.

One point that struck me from his post is how much the calculation preferences probably fell down to convenience and the availability of tables ? I wouldn?t be surprised if far fewer astrologers deliberated on the philosophical and astronomical principles involved than we assume would do that.

I tend to believe that whatever tables were available had the last word, and many (if not all) astrologers simply didn't think about the basis of the calculations. They used the tables at hand.

I tend to avoid getting into the mathematical discussions regarding ancient zodiacs. I simply note the positions of planets given in the texts and work from there. Then I test theories in modern day charts. (Which I will do a bit later with charts from Dorian Greenbarum's book on temperament.)

I know that Rumen Kolev and those who follow the Fagan-Bradley school swear by "the (one and only!) fixed Babylonian zodiac based on Spica at 29 Virgo and Aldebaran/Antares at 15 Taurus/Scorpio. But I reserve judgement on such specifics without more textual support.

Therese

Chris Brennan wrote:

Aside from that, Jones recently published an important paper in Ptolemy in Perspective where he tabulates all of the existing horoscopes and basically points out that the values were largely sidereal during the early Hellenistic tradition, and it wasn't until a few centuries after Ptolemy that a distinct transition took place where the charts became tropical. It seems like this is more or less the same conclusion that Dimityr Kojuharov came to in the thread that Therese quoted earlier, although in Jones' case his paper has been published, so it is open for review.

Whoa!! Checked it out on Amazon. Lowest price is $115 U.S. dollars. Amazon price is $189. Do you have the book, Chris? Is there a way we can get only the relevant section of the book?

Deb: I've replied to you privately.

handn wrote:I would say 'sky'. The background is arguably simply the sky itself, first and foremost. The fixed stars and/or the crossing and turning points can be used as reference points for seeing meaning, but there is no need to define the ecliptic in terms of either the stars or the crossing+turning points. The path of the Sun exists in and of itself, up there in the vault of the heavens.

Yes, but it is not measurable/plottable except with reference to something both visible and (relatively) unchanging. That's the fixed stars. Historically, therefore, the ecliptic was discovered and defined with reference to them.

Therese Hamilton wrote: --------------------------------------------------

by Dimityr Kojuharov on Tue Oct 18, 2011 11:13 am

Q: Can you give an internet reference for Alexander Jones?

Alexander Jones, Astronomical Papyri from Oxyrchynchus, volumes 1 and 2, Philadelphia, 1999

The most impressive statement of A. Jones is on the p.49 of his book, where he says that the Greek astrologers(after Ptolemy) used Ptolemy's tropical longitudes from Handy tables and then they used a special formula (Theon's rule) to convert these tropical longitudes into the sidereal. So the final result is a horoscope in a sidereal zodiac.
Dimityr Kojuharov
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Therese

HERE (a part of) THE TEXT_SOURCE FOM THE BOOK
http://screencast.com/t/bKYQzJZc8xpk