Did Greek Astronomers Have Access to Such?

Standard Ancient Greek Method's Math Triply Points
at Late Ancient Use of That Century's Eclipse Records

The Five Lunar Eclipses: 1292BC, 1274BC, 1245BC, 1201BC, 1190BC

Single Fruitful Theory Is Consistent With Integral Solution of Last 3
Hitherto-Mysterious Ancient Period-Relations. Each On-the-Nose.

Dennis Rawlins           2007 December 21

  • Summary (See also tight precis of entire case at inside cover of DIO 16 [2009].)
    At the end of the 20th century, only three precise ancient lunar period-relations yet remained unsolved.
    [“Period-relations” are integral ratios of celestial speeds, the central ancient one being the very accurate equation of 251 synodic months with 269 anomalistic months. The better known Meton→Easter relation, equating 19 years with 235 months, is far less accurate.
    (Neither of these are among the triple-quarry sought below.)]

    Testimony on these 3 relations had come down to us from sources spread across nearly half a millennium: from the 3rd century BC to the 2nd century AD.

    Yet in 2002-2003, it was discovered by DIO that all three period-relations were precisely consistent with common-prime-defactored integral eclipse-cycles and thereby explainable by the theory that the period-relations' classical-era discoverers had, using the only method attested in antiquity for finding such period-relations (that of Almajest 4.2&6.9), simply compared their own eclipse observations to records of eclipse observations within plus-or-minus 1/2 century of about 1240BC.
    Thus, one single fruitful theory — rooted in one single hitherto utterly unconsidered century — simultaneously reveals the origins of all three of the only hitherto-unsolved highly accurate ancient lunar period-relations.

    There are no less than six obvious evidences recommending the theory. These are summarized at DIO 11.1 [2002] ‡3 §§C3-8 [pp.21-22] — note ESPECIALLY §§C4-C5.)
    [See also DIO 20 [2012] ‡3 §L2 & n.23 [p.33].
    When this case is looked back upon someday, it will be apparent that a prime reason that this approach was not considered was that scholars (including DR) had uniformly discounted the very idea of such early eclipse records surviving for a millennium. (Note: DR was not smarter than others here. He was simply dragged into new temporal territory by the math of the situation.)]

    Our time-bases' vastness — over 1000y in each case — can also account for the previously-inexplicable astonishing accuracy of all three of these period-relations.
    [The Almajest (e.g., 3.1, 4.6, 9.2) explicitly recommends the obvious: long time-bases, for those seeking accuracy and thus long-term tabular reliability.]
    Each's accuracy is ordmag one part in a million or better — ten million in the draconitic case. (So since there are three equations & three super-accuracies, we are actually solving not 3 but 6 mysteries at one Occamite swoop.)
    [Note, also, that other anciently attested lunar period-relations (also founded on ordmag 1000y time-bases) are equally accurate, e.g., 251 syn.mo. = 269 anom.mo., 1979 syn.mo. = 160 sid.yr. (Both discussed at DIO 6 [1996].)]

  • DR's theory is indeed shocking: classical-era access to accurate eclipse-times over half a millennium older than the previously-accepted limit of eclipse-data availability (more reliable than the Ammizaduga data) — so shocking, that some historians reject the idea purely on the basis of the enormity of the remoteness.
    [Ptolemy refers (Almajest 4.11) to a series of eclipses brought over from Babylon, but does not give the duration of it. Some, e.g., Toomer 1984 p.166 n.59, point to the Almajest 3.7 statement that only from the 8th century BC on, are records on the whole preserved down to Ptolemy's time. But Ptolemy seems only to be saying that pretty complete then-surviving records start around then; he never says that no astronomical data at all survived from eariler. (We know some data did: the Ammizaduga record.) Also: note that Hipparchos' time isn't Ptolemy's time: one is 1100y later than the 13th century BC; the other, 30% longer — later by 3 centuries of potential time-ravages. Caesar's burning of part of the Alexandria Library occurred during that time.]

  • However, doubters of the eclipse solutions ought to recognize that not one but several possibilities inherently reside in the remoteness-enormity of DR's proposed Babylonian eclipse-records:

    1. The very idea is crackpot.
      [Easy to undo that complaint, since older data are known, and the method proposed here to explain the three integral equations is common-sense, highly accurate, and very naturally emits integral relations — self-evidently apt for solving the sources of equations which are entirely expressed in integral form. Our method is also attested and standard for the era, since the best ancient scientists understood its advantages.]

    2. The proposal is possible but not strongly so.
      Gauging probability-inherence of our proposed matches occurring by chance is discussed below. Several soft & hard probability-tests have already been applied: DIO 11.1 [2002] ‡3 §E [pp.24-25]; and DIO 13.1 [2003] ‡2 §C [p.13]. Results: odds against chance are statistically significant, if not lock-certain. Below, we have chain-linked these various surprisingly confirmatory indicia, four such in all:
      just keep on clicking upon each's glowing link, starting with this link, to go right on to the next (ultimately returning here).

    3. The very enormity of astronomical-historian-clique shock tells us that if the proposal is true, it represents a clarifying advance in our perception of the devoted preservation (and possibly precision) of early Assyrian-Babylonian astronomical records — long before the Persian and Greek conquests of Babylonia.

    4. If the theory is ultimately accepted, it also may be of some ancillary use — as a non-extrapolated snapshot (DIO 11.1 [2002] ‡3 §D5 [p.23], for one felicitously remote century — to expert extrapolative researches on ΔT behavior, possibly assisting in suggesting an upper bound on ΔT for that century.

  • Keep in mind: if the hypothesized 13th century data had survived to our day, there would be no inductive achievement here. I.e., there is no sense in attacking an unexpected induction of lost science — on the grounds that it's lost! Inductions of lost data obviously must be judged on merits other than the self-evident fact of lostness.
    [DIO 11.1 [2002] ‡2 n.7 [p.12]: “If we cannot accept any finding in ancient science without direct attestation, then: should we all park our brains at the entrance to the ancient science field? Is it forbidden to induce beyond the texts?”
    Note that there are several pieces of ancient astronomy which are not mentioned in extant classical-era materials, yet which we know existed: e.g., a valid Alexandria winter solstice solar altitude observation (DR Isis 1982); Hipparchos' two obliquities 23°11/12 & 23°2/3 (PASP 1982), the latter triply verified; his early and late solar orbits (the latter recognized since 2001 in the Encyclopedia of Astronomy & Astrophysics); not to mention the Ammizaduga Venus data (which still exist).]

  • Integral Relation→Integral Relation
    — From Visible Empirical ECLIPSE-CYCLE to Tabular PERIOD-RELATION
    We know that all pre-Ptolemy lunar speeds were based upon period relations found from observed (visible) eclipse-cycles of ordmag 1000y, where any prime factor common to both sides of each empirical eclipse-relation was naturally extracted before said relation (generally invisible outdoors, once the prime factor was removed) became established as the convenient computational basis of astronomers' tables, and thereby came down to us in the pleasingly compact integral format which we are about to start sampling.
    [For independent evidence that accurate lunar-orbit elements were based upon eclipse-observations, see elsewhere.]

  • Ptolemy explains the centrality of just this process at Almajest 4.2, when he discusses the most important (DIO 11.1 [2002]) ‡1) of empirical anciently known periodicities, the visible 345y-long eclipse cycle

    4267 synodic months = 4573 anomalistic months (Greek; un-attested in Babylon)

    which was repeatedly verified empirically as of a duration (126007d01h) virtually independent of position (proving its anomalistic cyclicity). Thus, division by common-prime 17 provided the canonical and extremely accurate period-relation:

    251 synodic months = 269 anomalistic months (System B, Babylon)

  • Inverting the Foregoing Process — to Untransform
    Three famous but hitherto-unsolved integral lunisolar period-relations are found on texts of the classical period. (No selectivity here: as of the start of 2002, these were the only outstanding ancient lunisolar period-relations remaining to be solved.)

    [1] 6247 synodic months = 6695 anomalistic months (System A, 3rd century BC)

    [2] 5458 synodic months = 5923  draconitic  months (Hipparchos, 2nd century BC)

    [3] 3277 synodic months = 3512 anomalistic months (PlanHyp, 2nd century AD)
    [Note that in what follows we will often use abbreviations for lunar periods: u for synodic, v for anomalistic, w for draconitic.
    Thus, the foregoing will henceforth below often be written like: [1] 6247u = 6695v, [2] 5458u = 5923w, [3] 3277u = 3512v.
    (Or as ratios: [1] 6247u/6695v, [2] 5458u/5923w, [3] 3277u/3512v.)]

  • Conservative Math Automatically Yields Way-Unconservative Triple Discovery:
    What could possibly be more obvious and conservative than to use ancients'

    elementary-arithmetic standard method of discovering period-relations?

    Therefore, DR just probed (2002/3/18-2003/1/26) via the simplest, most astronomically-sound, and only-attested technique: Ptolemy's common-sense method — which we just invert for each equation. For all three variously disparate cases, the unambiguous recovery-math was mere multiplication by an integer (or half-integer: DIO 11.1 [2002] ‡3 §B1 [p.20]) — hey, how hard was that?!
    The three DR inductions' directness — leading (unambiguously in all three cases) to data in the range 1292BC-1190BC is what others must verify before they either accept or reject the theory. After DR's exhaustive 2001-2003 investigations, he has consistently contended that no post-1500 BC data, other than the c.13th century BC eclipse records cited, will [a] directly (by attested ancient procedure) and [b] exactly produce all six integers (24 digits) of the three quarry period-relations, connecting to eclipses of the very same subsequent eras when extant testimony for each of the 3 relations first appears.
    (NB: no opposing theory can satisfy either [a]or[b]. Indeed, no other contending theory automatically produces integers at all — especially ones of appropriate dimensions — and in exact agreement with every one of the six attested ancient lunar-speed integers: that's twenty-four hits upon twenty-four digits.)
    In the years since 2002-2003 publication, not one alternate eclipse has been found by any of the several committed cultist knee-jerk disbelievers in the DR theory. This, despite fervent desire among them (particularly AJ, PH, &JB) to find some way — any way — to kill off DR's eclipse theory. Note that those (esp. AJ) who reject the theory because of the proposed eclipses' great antiquity are engaging in literally preposterous logic. Such mental inversion is typical of math-challenged cultists who (selectively) balk at going beyond the directly attested.
    [Yes, deductive logic indeed tells us that only flawed premises can lead to a false conclusion, but it is the inverse of reason to Jonesely attack an evidential argument-towards-a-conclusion by rejecting the conclusion a-priori merely in order to devalue the argument by then going backwards to damn what has led to the supposedly impossible conclusion — in this case the remoteness of the adduced early eclipses — and to create the prescribed illusion of invalidity, for the newly discovered heretical proposal, by ignoring the force of a battering-ram series of unsubtle new evidences in favor of it — all this in order to instead concentrate upon a single, old, traditional, supposed-Fatal-Flaw in DR's proposal (the objection that 5458u/5923v allegedly existed on Babylonian texts written long before Hipparchos: ibid §D1 [p.22]), a “Fatal-Flaw” which ironically has now unexpectedly — after a 1/2 century of loyal forgot-to-read-the-fine-print acceptance — been found (idem) to itself be Fatally Flawed, as regards the rock-surety it so long pretended-to.]

  • To the contrary, the very import of the DIO triple-discovery IS the antiquity which is rigorously indicated by the uniqueness of the three solutions — ALL THREE pointing towards classical-era use of eclipse data from the SAME ULTRA-REMOTE CENTURY (1292BC-1190BC) — and this NO MATTER WHETHER the later astronomers are from the 3rd century BC or the 2nd century AD, half a millennium apart.

  • In each case, DR's solution remarkably LED RIGHT TO the close vicinity of the 13th century BC.
    The underlying eclipse-relations were (length in years, respectively, about 1010y, 1103y, 1325y):

    [1] 12494 synodic months = 13390 anomalistic months (System A, 3rd century BC)

    [2] 13645 synodic months = 14807 1/2 drac months (Hipparchos, 2nd century BC)

    [3] 16385 synodic months = 17560 anom months (PlanetaryHyp, 2nd century AD)

  • Verifications:

    1. To check the connexions, divide each of these 3 hitherto-unknown eclipse-cycles by its corresponding period-relation to see how simple the ratios are:
      [1] two;
      [2] five halves;
      [3] five;
      again: how hard was that?

    2. To supersimply verify the 13th century BC clustering, just subtract the relations' durations from the approximate dates of their attestation, for century-rounded estimates:
      c.300 BC − 1010y ≈ 1300 BC;
      c.100 BC − 1103y ≈ 1200 BC;
      c.100 AD − 1325y ≈ 1200 BC;
      again, this isn't higher math. For most of us.

  • That, in skeletal outline, is what has been uncovered. And probably no set of discoveries in ancient astronomy has been more ordinary (in method or math-execution) or more unexpected (in result) by all — certainly including DR. Since history of astronomy archons are reluctant learners, there will be disbelief in officialdom at how easily and directly such treasure was captured.
    [Upon hearing of DR's eclipse-solutions to the three famous hitherto-intractable period-relations, Morphiosi doubtless immediately suspected the matches were rigged.
    (After all, that's how they get some of their own matches:
    DIO 16 [2009] ‡3 eqs.7\&14 & n.38 [pp.27\&30] and §J5 [p.36];
    DIO 20 [2012] ‡3 §§K4-K6 and nn.19&22 [pp.31&32].)
    Years later, the seethers are still at the eternally frustrating task of finding the slightest evidence that the DR solutions are anything but what fell naturally out of an unprejudiced, non-manipulated investigation via the only anciently attested method for finding lunar period-relations.]

  • It is true that the the implications here may subtract from the rep of decaying post-Arbela Babylon. But we should have been realistic all along. There is, e.g., no sign in late Babylon of the sophistication we find in contemporary Hellenistic math — i.e., there's no known Seleukid Euklid.
    [DR's bluntness about Babylonian astrology's mathematical inferiority to Hellenstic astronomy (after 300BC) has not won him any archonal friends. Babylon: no trig, no transit circle, no vertical observations, no solstice or equinox observations (Neugebauer HAMA p.366; Jones 2005), no awareness of lunar parallax, or precession, observations of needlessly rough accuracy (see F.R.Stephenson's consistent findings or DIO 1.3 [1991] n.223 [p.152]), no knowledge of (or even evident interest in) Babylon's geographical latitude, planets taken in good-to-bad astrological order instead of the Greeks' physical order. (Summation: DIO 1.2 [1991] §E3 [p.112].)]
    But DR's discovery that Greeks used Babylonian 13th century BC eclipse records adds to the glory of the height of early Babylonian civilization — a thousand years before Greece became serious about astronomy — a revelation that ought to appeal to cliques who have long affected a love of Babylonian astronomy — a passion which evidently becomes somewhat “confused” when Babylon is exalted from Unapproved quarters:

    the resulting denier-funhouse is starkly delineated at DIO 11.1 [2002] p.26.

    [There is little doubt that 13th century BC Babylonia was more than advanced enough to care to record simple eclipse-data. E.g., the Hilprecht Collection in Jena possesses a strikingly precise clay tablet map of Nippur, Babylonia, from c.1300 BC.]

  • To assist predictably glacial archonal realization of what has been found, the following less condensed discussions may be of enlightening value.

  • Contextual Considerations:

    1. It is not at all controversial that Greek astronomy had access to Babylonian records of eclipses and planetary data. And Babylonian celestial data much older than the 13th century BC have survived far longer (c.1500BC→present for the Ammizaduga Venus tablets: 3500y) than the data-survivals proposed here (1010y, 1103y, 1325y).
      [And over 99% of classical-era science mss have been lost. (Less than 10% of even Hipparchos' writings survive. Under 1% [perhaps 0% of primary writings] for Aristarchos.) Which makes it hard to be confident — as confident as certain moderns, anyway — that we would know of classical-era references to 13th century data if astronomers of that time had used them. After all, there are no such references to the earlier Ammizaduga data — which we know existed.]

    2. All pre-Ptolemy lunar speeds are attested by Ptolemy as having been based upon period-relations obtained from long eclipse cycles. (Almajest 4.2 & 6.9; Toomer 1984 Almajest pp.176 & 309.)
      [Note that Ptolemy's top modern defenders reject his direct testimony here on method. See, e.g., O.Neugebauer HAMA pp.310-311 & 391, or Toomer 1984 Almajest p.176 n.10.]
      Take, e.g., 251 syn mos = 269 anom mos: its accuracy — 1 part in millions — was based upon the 345y eclipse-cycle (which is 17 times the 251-month relation), just as Ptolemy says at Almajest 4.2. This is obvious to any astronomer familiar with how astronomical periods are determined accurately: record a huge time base T for a known number N of cycle-repeats, then the mean-motion's period P is found via

      P = T/N.

      The idea is that the observational errors at each end of the span are automatically reduced to relative insignificance after division by the large number N.
      E.g., when errors of ordmag 1h (3600s) at each end of a 345y cycle are divided by 4267, the period (month M) is obviously determined to ordmag 1 time-second.]

    3. All 3 ancient month-estimates are accurate to ordmag 1 in (at least) a million, not accomplishable (in a naked-eye era) without vast time-bases.

    4. All 3 are anciently reported in integral-ratio form, exactly the form which empirical eclipse cycles would emit, simply & naturally — merely through dividing by an integer (or half-integer).

    5. When we attempt to reconstruct the ancients' three hitherto-unsolved ratios (from System A, Hipparchos, & Ptolemy) by undoing such division (i.e., multiplying by an integer), we find: all three reconstructions lead into the same narrow 10-decade temporal window, the 13th century BC, and all three do so unambiguouslydespite the fact that they come from eras centuries apart (spread over nearly 1/2 a millennium). I.e., the front-end eclipses are conspicuously four times as tightly bunched (into the same 13th century BC) as the back-end eclipses which are spread throughout the classical era. [I.e., the three results all zero-in on an early theoretical span (c.100y: 1292 BC to 1190 BC) which is about four times narrower than the later empirical base: 3 different observers, spanning over 400y: mid-3rd century BC to late 2nd century AD.]
      This provocative over-arching statistical point is one which the history-of-astronomy community has yet to take in (a point independent of whether it will be persuasive, even if&when finally understood). And said general point is merely prelude to presentation of some specific matches yet to come (below: as the earlier-cited chain-links continue), which multiplicatively shrink even further the statistical likelihood of chance-explanation here.

    6. Starting in 1980, historians refused for nearly 1/4 century to accept that all Greek planet speeds were also based upon cycles, even though DR had shown that three planets' mean motions (Mercury, Venus, & Saturn) positively were — and that the numbers generating their speeds were right in the Almajest 9.3 preface to their tables. Then (DIO 11.2 [2003]) Alex Jones showed (while correcting a DR misjudgement) that the mean motions of Mars & Jupiter were also based upon cycles cited in the same preface — ending that controversy.

    7. DR has traced (idem) all five planets' Almajest mean motions to integral sidereal cycles of ordmag 1000y. (Note the Jupiter case's glaring indication that the Almajest's tropical or Metonic planet relations must have come from larger sidereal relations: DIO 11.2 [2003] ‡4 §H4 [p.45].) And we note that Ptolemy's Planetary Hypotheses explicitly provides such huge sidereal cycles for the planets (Neugebauer HAMA p.906), sidereal-integral being the sort of speeds which ancient observers would find from centuries of raw stationary-point planet data (ibid p.390) — just as synodic-integral are the sorts of lunar speeds one would find from eclipse-cycles, and are precisely the format of the lunar speeds we find in pre-Ptolemy records.
      So DR has proposed his General Theory of Ancients' Cyclicities (DIO 11.1 [2002] ‡2 §H [p.19]): all ancient celestial mean motions were ultimately based upon integral cycles — the Moon, the 5 planets, even the Sun's accurate sidereal motion (DIO 6 [1996] ‡1 eqs.23&31 [pp.22&24]), and Aristachos' durable inaccurate precession (arising out of his 4868y-cycle Great Year: DIO 11.1 [2002] ‡1 eq.11 [p.8]; DIO 9.1 [1999] ‡3 eq.16 [p.37]). Since there is no longer any question that ancients' planet motions were based upon cycles, isn't the analogy obvious regarding ancient scientists' likely approach to determining lunar motions?

  • What Led DR to His Eclipse-Cycle Triple?
    We repeat the surprisingly-ultra-conservative answer: DR simply took ancient scientists' STANDARD METHOD — that is, their use of very long eclipse cycles — to search out the sources of three previously unsolved problems.

  • In no case was there serious ambiguity: ALL 3 arithmetically-indicated early eclipses directly plopped down into the 13th century BC or barely after. We examine these shockers one-by-one, in order of date and (equivalently, as it happens) of DR discovery.
    [According to the 1992 canons of Meeus-Mücke and Liu-Fiala (both works based upon F.R.Stephenson's pioneering researches), each of the ten eclipses used here were above the appropriate horizon for at least part of the event's duration.
    (The relation of visibility and ΔT questions are touched on in a 2008 note appended to the online pdf of DIO 13.1 ‡2 §G [p.17].)
    In any case, the σ in ΔT is roughly 1000 time-sec at that epoch: Stephenson, conversation, 2007/11/29. Stephenson warns at JHA 39:229-250 (2008) p.230 that, before 1000BC, extrapolation using his induced acceleration should treat it as “a first approximation”. The closest eclipse to being eliminated by such extrapolation is that of 1245BC/11/13 (which is the front half of the most convincing of the pairings). Note that, though we cannot on such a basis prove whether or not this eclipse was seen, that very situation reflects the present paper's potential modern scientific utility.]

  • Solution [1]: System A:
    The characteristic integral equation defining System A (found only on Babylonian tablets) is a period-relation of length c.505y (Neugebauer HAMA pp.478 & 501):

    6247 synodic months = 6695 anomalistic months

    [See, e.g., J.Britton Arch Hist Exact Sci 61:83-145 [2007] p.124. (The relation is mis-typed there.) There is no citation of DR's proposal that the 6247u relation was obtained, not by Britton's wildly speculative theory of massive averaging of elaborately-elicited Lunar-Four-based anomalistic estimates (there's not-a-jot of ancient testimony that anyone computed lunar speeds so), but simply through dividing an eclipse-cycle by a small integer: below; or DR DIO 11.1 [2002] ‡2 §A4 [p.12]. (Non-citation of this simple, conventional proposal occurs even though the same DIO issue is cited for carping purposes at Britton n.66.)]

    Well, given [a] Ptolemy's ascription of all pre-Ptolemy lunar speeds to integral eclipse-cycle bases; [b] his account (based upon division by an integer) of the ancestry (above) of the 251-month period-relation; [c] the fact that eclipses are the most obvious, naturally integral, and accurate way to establish such ratios — it is reasonable to explore whether the above System A period-relation is (like the 251-month period-relation) also an eclipse-cycle simply divided by an integer. But, since the equation is over 500y long, our options are (quite) limited — i.e., the integer 2 is all there is. (If it fails, then: game-over.)
    But when (2002/3/18) DR tried multiplication by 2, he was delighted to find that (against the a priori odds) the result was a valid eclipse-cycle (c.1010y long, our above cycle [1]) — which is recalled here:

    12494 syn mo = 13390 anom mo = 13358 1/2 drac mo − 22°

    The 22° remainder is so near the limit that allows eclipse-pairs to occur at all, that such pairs are rare — fortunate in helping delimit possibilities for those which underlay period-relation [1].
    [Only three post-400BC pairs could have been used. These are listed at DIO 11.1 [2002] ‡2 §B4 [p.13], (Due to a DR book-keeping error, a half-invisible 1418BC-408BC pair was accidentally listed there. However, the pair was not used in any analysis originally or latterly. The online version of DIO 11.1 [2002] has deleted the pair, as well as righting an equally harmless but equally disgraceful typo at ‡3 n.11 [p.22].)]
    The search for pairs that are suspect of thus triggering the invention of System A find (between 336BC and 67AD) merely two pair:


    (DIO 11.1 [2002] ‡2 §B4 [p.13].) Presumably the to-the-hour agreement between the two pairs' time-gaps suggested an anomalistic return. The possibility that 13th century BC eclipse reports specified the time (not just date) of the eclipse could be a hint of early precision-astronomy; however, the fact that most (all but the 1st) of the five older eclipses (underlying the present triple-analysis) were near the horizon suggests the possibility that near-horizon eclipse reports were preferentially selected in order to narrow the event's time-uncertainty (a technique still used today by experts in ΔT research) — which further implies that enough records survived (contra DR's initial 2002 impression) to permit later scientists' selectivity. Finally, when we learn (ibid [2002] §E6 [p.18]) that the earliest cuneiform tablet firmly connected to System A starts its computations (of lunar positions) from only a few months after the 263BC eclipse, the coincidence is most gratifying.

  • Solution [2]: Hipparchos' Draconitic Month:
    At Almajest 6.9 (Toomer 1984 Almajest p.309), we find Ptolemy reporting in-effect the Hipparchos ratio or — period-relation — that the draconitic month equals 716/777 of a synodic month, for expressing the draconitic (eclipse) month discovered by Hipparchos.

    716 synodic months = 777 draconitic mo = 767 anom mo + 124°.8 ≈ 21143d.9 = 57y.9

    (For simplicity in this equation, we use the remainders implied by his parameters, which are close to reality.)
    [The “draconitic month” or “eclipse month” is the time the mean Moon takes to return to a node. A visible (umbral) eclipse can only occur within about a dozen degrees of a node.] Though this is not an eclipse cycle as its stands, we could (if this is all we had testimony for) recover the eclipse cycle empirically underlying the equation merely by finding when a multiple of the equation produces regularly-repeating eclipses. Here, multiplying by 10 does it, producing the following eclipse cycle:

    7160 synodic months = 7770 draconitic mo = 7673 1/2 anom mo −12° ≈ 211439d ≈ 579y

    (Accurate to about 1 part in 2 million.) The 1st of these equations (716 mos) is of course an obvious consequent of the 2nd, via simple division by common primes — 2 and 5 in this case (thus the 1st equation is 1/10th the 2nd equation).

  • Now comes the disjunct-impediment (which DIO 11.1 [2002] ‡3 finally [2002/4/3-4] penetrated past): Ptolemy says (loc cit) that the foregoing 7160 mo eclipse cycle produces Hipparchos' famous draconitic period-relation (already given earlier at Almajest 4.2: Toomer 1984 p.176), which was accurate to 1 part in ordmag 10 million:

    5458 synodic months = 5923 draconitic mo

    But in fact Ptolemy is (partly) wrong: this equation positively does not follow from the above 7160 month eclipse cycle.
    [The disagreement is about 1 part in 2 million. Small, yes. But the two ratios are definitely incompatible, so 5458u = 5923w cannot have arisen from the 7160u = 7770w cycle. Neugebauer HAMA p.314 argues that the discrepancy is due to slight deviations (which Ptolemy notes) from the exact apsidal line. The problem no pre-DIO investigator faced is that such a consideration would've ruined the purely integral ratio Hipparchos concluded for. Had he been concerned with the trivial effect of the imperfections so blinding to previous modern investigators, he would at the very least have appended remainders to the integers of his ratio (as for the adjusted period-relations of Almajest 9.3). But he didn't. Instead, he adopted a simple integral ratio whose components are about the size one would expect if the ratio was based upon a centuries-long eclipse cycle's ratio — exactly as Hipparchos has already done at Almajest 6.9 for the very same problem (and at Almajest 4.2 for anomalistic motion, as we note below), despite the very same sort of minor imperfections' presence. (Do those who hang-stubborn on this point seriously imagine that after Hipparchos corrected for imperfections he then took the trouble to use continued fractions to find an integral ratio with such small components [merely 4 digits each] as to make it falsely appear that a different eclipse cycle than the 7160u/7770w one was his empirical basis? We already know from Almajest 4.2 that Hipparchos took a simple, uncorrected eclipse cycle-based plain integral ratio (251u/269v) for his anomalistic speed. Why should he act differently for his draconitic speed? — except to proactively save the faces of modern history-of-astronomy archons who cannot abide the spectacle of non-cultist scholars finding neat potential solutions to problems which they themselves never thought to approach except in herd-zombiestep.)]

  • DR found that the above 5458 month cycle follows instead from cycle-pairing an earlier eclipse with the very same −140/1/27 eclipse (Almajest 6.5) which Hipparchos had initially used (Almajest 6.9) to find the 7160 month cycle,
    [Hipparchos perhaps made a similar decision (much less successfully, given the less accurate data he inherited for prior generations' solar places) after recording his 135BC Summer Solstice, when he used it to gauge the length of the tropical year by comparing to an earlier solstice. He evidently switched from using Meton's 432BC solstice as his older datum (DIO 1.1 [1991] ‡6), to using Aristarchos' 280BC solstice instead (Almajest 3.1). In both cases, use of the older datum gave better results (despite large errors in both antique data), simply because of the longer time-base T — which points up the advantage of using such long bases, an advantage understood by all but Muffiosi.]

  • The search for a parent eclipse-cycle that is proportional to this period-relation is again narrowly restricted, since the latter is already long: 441y. But, again, a little testing elicits the solution (DIO 11.1 [2002]) ‡3 §§B2-B3 [p.21]): multiplication by 5/2 discovers an eclipse-cycle ([2]) about 1103y long:

    13645 synodic months = 14807 1/2 draconitic months = 14623 1/2 anomalistic mo + 7°

    The half-integral anomalistic term requires: only apogee-perigee pairs need apply.
    [Any pair (of the type specified by Ptolemy) with identical anomaly would have sufficed; but Hipparchos apparently preferred to try eliminating (as completely as possible) differences between true and mean longitude, by using events near the lunar orbit's major axis. (With analogous cleverness, he usually observed the Moon when its longitudinal parallax was near null: Almajest 5.3&5.)]
    It happens that the nearest-to-perigee eclipse during Hipparchos' lifetime that works with the 13645-month cycle is that of 141BC/1/27 (anomaly −1°), which we know he recorded at Rhodos — and is the very eclipse which Almajest 6.9 says he once paired with the apogee eclipse of 720BC/3/8 (to produce the above 7160-month eclipse-cycle). But if we instead apply the 13645-month eclipse-cycle (behind Hipparchos' actual 5458-month period) to the very same 141BC eclipse, we find his choice of earlier apogee-eclipse and see that the chosen eclipse-pair was:


    — and we find that modern theory indicates that the end of the 1245BC eclipse was probably just above the horizon in Babylon and was near-apogee as required (anomaly = 171°).
    [DIO 11.1 [2002] ‡3 §C2 [p.21] suggests the 1239BC/7/12-136BC/9/24 pair, alternatively.]

  • The fact that the astronomy of the above 13645-month eclipse-cycle requires a perigee-apogee pair is striking because Hipparchos is the only astronomer in history who is known to have tried such a ploy (Almajest 6.9). That is, the 13645-month cycle's half-integral anomaly shouts Hipparchos. And, though Ptolemy is not always reliable, it is worth noting that he (Almajest 4.2) explicitly credits Hipparchus with the wonderfully accurate 5458-month relation.
    [Firmly establishing the 4267-month eclipse-cycle or cycle [1] or cycle [3] requires multiple eclipse-pairs. But once the synodic and anomalistic motions are nailed down (preferably by the 251-month period-relation, or cycle [3]), one needs but a single well-chosen equal-magnitude eclipse-pair to establish draconitic-return cycle [2]. This is why DIO's establishment of all three cycles has required five eclipse pairs: 2+1+2 = 5.]

  • Solution [3]: Ptolemy's Anomalistic Equation :
    At c.160AD, Ptolemy in the Planetary Hypotheses 1.1.6 provides the following period-relation

    3277 synodic months = 3512 anomalistic months

    Here there are two possible integers (which will by multiplication produce an eclipse cycle not too outlandishly long): 3 and 5. But the former produces no eclipse pairs after 36BC until the mid-3rd century AD, while the latter connects to two eclipses reported in the Almajest, compiled by the very author (Ptolemy) whose Planetary Hypotheses left us relation [3]. Which suggests that the associated pairs helped found the above period-relation. So, multiplying it by 5, we have — at c.1325y! — the longest cycle ever seriously proposed for determining accurate ancient parameters (of course, it would figure that the longest cycle would originate from later rather than earlier antiquity):

    16385 synodic months = 17560 anomalistic months

    Again against chance expectation (continuing the train of indicia suggesting we are on the right track here throughout), Ptolemy reports eclipses in 125/4/5 and 136/3/6 that work with the above eclipse cycle. (The odds are 20-to-1 against his selection occurring by chance: computed at DIO 13.1 [2003] ‡2 §C1 [p.13].) Thus, applying the 13645-month eclipse-cycle to those, we find two pairs that could have handed him that cycle's durations (which produce exactly period-relation [[3]):


    Note that it makes sense that Ptolemy would not attempt to find a period-relation better than the famous one of 251 months unless he were using a huge time-base — which he appears also to do elsewhere (DIO 11.2 [2003] §L [pp.49-50]) in the same PlanHyp.

  • Temporal Coherence:
    The earlier eclipses just derived are only about a century later than the earliest we adduced (above) for System A — emphasizing the tightness of the temporal window here, where all five of our remote eclipses fall in a one-century space, though arising from period-relations established throughout high antiquity over a span of over four centuries: 281BC to 136AD. We list those used-eclipses (recovered here) in the order of chronology and duration.
    System A 1010y 281BC&263BC↔1292BC&1274BC
    Hipp 1103y 141BC↔1245BC
    Ptol 1325y 125AD&136AD↔1201BC&1190BC

  • Ancients may, if several relations seemed comparably useful, have chosen the one where both sides of the equation contained a common prime, which rendered the final relation less cumbersome.
    [Hipparchos' alternate draconitic eclipse-cycle, 7160 synodic months = 7770 draconitic months was divisible on both sides by 10, leading to the {\ti Almajest} 6.9 period-relation 716 syn mo = 777 drac mos. If there were no common prime factor, then the period-relation was identical to the eclipse-cycle and thus directly obvious — e.g., 781 sidereal years = 9660 synodic months, which was used to develop Ptolemy's final luni-solar equation (DIO 6 [1996] ‡1 eqs.20-31 [pp.21-24]). This and other period-relations were not anomalistically integral but were used anyway — another neat example being 800 sid yrs = 9895 syn mos, was divided by 5 to give Geminos' 160 sidereal years = 1979 syn mos.]

  • Responses to Objections:
    As with so many of DR's discoveries, at first only the most enlightened are taking this seriously. Centrists imagine (hope?) that there is some impediment that all-by-itself makes the hypothesis flat-impossible. After a century of Babylonian-astronomy-exaltation, the findings here are obviously an unwelcome shock.
    [A dozen years after publication, not one professional historian has yet reported checking even the easy arithmetic, much less the more laborious task (which may be beyond the abilities of some among the set) of confirming the delicate behavior of the eclipse-cycles we discuss. I.e., historians-of-astronomy are again learning nothing from their own history.
    (But, then, there's the old saying that the one thing we learn from history is that most folks learn nothing else from it.)]

    So let us look critically at the most predictable objections:
    [a] Data so remote couldn't have survived.
    Yet the Ammizaduga Venus data have come through to us, and they are quite pre-13th century. Recall too that the availability of pre-747BC lunar records is indicated by Geminos' reportage of the 800y sidereal lunar cycle: DIO 11.1 [2002] ‡2 §G3 [p.19]. And it is hardly outré to suggest that Babylonians were observing in the 13th century BC: see, the slightly earlier 1350 BC estimate at Isis 83:474 (1992). I.e. (despite cultist tendencies to Ptolemaically assume Right-Think before the bother of looking at mere data), there is nothing here that is a-priori inherently-impossible — which thereby dispenses with cemental minds' prime (unconscious) impediment to acceptance of our proposed theory.
    [b] Thousand-year cycles aren't in the Almajest .
    No, but they're in Ptolemy's Planetary Hypotheses (see, e.g., O.Neugebauer, HAMA p.906) for at least (DIO 11.2 [2003] ‡2 §L6 [p.50]) three planets: Mercury (993y), Venus (964y), & Mars (1010y). (Subtracting 1010y from 160AD, we see that 2nd century AD astronomers had access to celestial observations going back at least as far as 850 BC, more than a century earlier than is accepted by MuffThink.) Note: these cycles are sidereal — which is just what raw empirical observations yield. (Stationary-point returns: method well explained at O.Neugebauer HAMA 1975 p.390.)
    [c] The early eclipse-dates DR is proposing could not have been ascertained reliably enough before the Babylonian calendar became regular.
    Yet Ptolemy's eclipse trio (721BC-720BC) is correctly dated, for events well before said calendar became regular. Why assume that early Babylonian astronomers were not up to Ptolemy's smart habit of dating all by the unambiguously rigid Egyptian calendar?
    [d] There are cuneiform records using the 5458-month cycle c.200BC, well before Hipparchos.
    But this objection falls, upon detection of a flaw in tablet-dating firmness (noted elsewhere here and at DIO 11.1 [2002] ‡3 sect;§D1-D2 [pp.22-23]) — a point which shows that our findings have important implications (for Bablylonian datings) — well beyond the issue of the eclipses analysed here.
    [It turns out that the only explicitly dated Babylonian tablet that uses 5458u = 5923w was written a quarter century after Hipparchos.]

  • Creativity vs Creationism:
    For now, this paper may prove a vain exercise.
    In dealing with those who already know the wrongness of alternate theories even before looking at the evidence (in the present case, a seething clique, which has spent years straining to draw high-precision astronomy out of Babylonian not Greek records), DR feels a kinship with those scientists who (like himself) have debated creationists. The cementality is the same: no interest in what is the most reasonable explanation of the admittedly fragmentary data (though the present theory's mechanism is [unlike Darwin's] anciently attested), but an obsession instead with rejecting anything but a pre-arrived-at sacred conclusion (in this case: non-scientific Babylonian astrologer-mystics were the ultimate pre-Ptolemy astronomical genii) for which there is no evidence whatever on method — fragmentary or otherwise.

  • Mental Archaeology and the Future:
    Throughout his career, DR has enjoyed numerous vindications by emergent new evidence. The above theory will probably not be one of them, since 13th century BC cuneiform eclipse records are unlikely to turn up at this late date. But the case as it stands is sufficiently coherent, direct, and simple that (even if the theory is never 100% established) its merits will be gingerly appreciated by balanced scholars in the not-too-remote future.

    A theorist specializes in envisioning beyond available data, so the creator's vision of that future will for-now suffice as vindication in this matter — which is in any case of lesser importance, compared to DR's 2002-2003 combination of delight and initial-disbelief when experiencing the three discoveries themselves.

    Appendix 1. On Method: Standard Greek vs Double-Secret Babylonian.

  • DR does not at all object to any scientist who wishes to question the foregoing on logical or empirical grounds. But it is disappointing to observe the unscientifically passionate resentment of the theory, by a clique that has long been committed (professionally & emotionally) to ascribing the discovery of high-accuracy ancient lunar speeds to Babylonia, though:
    [1] The only proven relevant inter-cultural transmission of a mathematical parameter based upon known dated observations was in the direction Greece→Babylonia: the sole Babylonia-attested yearlength, found upon the key System B cuneiform tablet BM55555 (a DR discovery, now honored by the tablet's permanent display at the British Museum), based upon Summer Solstices by Meton (432BC) and Hipparchos (135BC).
    [B.L. van der Waerden's evaluation began the realization of this finding's import, and the discovery is now so universally accepted that it has long since entered the Encyclopedia of Astronomy and Astrophysics (2000, Hipparchos entry). See also A.Jones' generous paper in the Archimedes 2005 collection “Wrong for All the Right Reasons”.]
    [2] Even DR-critics' most adventurous unattested (purely hypothetical) Lunar-4or6 schemes would not automatically produce the integral-ratio format of all the high-accuracy extant pre-Ptolemy ancient lunar speeds. The cultists' pretzel-processes have never been able convincingly to account for the extant lunar speeds' precise integral ratios (which automatically issue from eclipse-cycles by attested methodology) and all the attested ratios' amazing accuracy.
    Babylonianist attempts to solve the three ratios' sources are based on crude horizon data that are less steady and less directly related to anomaly than eclipses' neat periodic returns, so these Muffia guesses must posit MASSIVE use of averaging, thus negating the use of merely two bounding events separated by a huge time-base — which all astronomers know is the preferred method for accurately determining steady temporal periods. (Not just for eclipses, but also for, e.g., rotations of planets or pulsars. Note that some cultists [e.g., P.Huber] propose explaining ancient period-relations by combining arbitrarily and flexibly-ad-hoc multiples of shorter relations (oblivious to the lack of ancient attestion of such transparent jugglery) — needlessly jettisoning the accuracy-advantage of using long ones. Astronomers instinctively understand this point. Without needing to be told.) The Greek-standard eclipse method (used by DR) fills all the above requirements perfectly naturally — indeed, effortlessly.
    DR has long contended that the “Babylonian” month's 1-in-millions accuracy was based simply upon the 4267 syn.mo. eclipse cycle's empirical invariance within under 1h (DIO 6 [1996] ‡1 fnn.18&56 [pp.6&13; DIO 11.1 [2002] ‡1 §A3 [p.6]; DIO 13.1 [2003] ‡2 §§E6-E7&F7 [pp.15&17]), since 1h/4267u ≈ 1/3,000,000. J.Britton, after for years questioning this basis for the Bab.mo., now agrees to it, and sets forth the same narrow sub-1h range of variation in the 4267u cycle: Arch. Hist. Exact Sci. 61:83-145 [2007] pp.123-124. Yet:
    [a] JB does not cite DR's confirmation here, though his calculations find and use the very same range which DR was (2002 ‡A3 [p.6]) perhaps first to quantify (in hours and in equations), tabulate, and use in this connexion (see above DIO citations).
    [Nor does JB cite DR elsewhere except at his n.66, where he cavils about periphery, not noting online DIO 11.1 [2002] ‡1 §A8 [p.7]'s admiration of his alternate rounding-approach for solving the Aristarchos month's source (that is, DR will cite a Britton priority, though the reverse isn't happening here [JB admits only DR's BM55555 solution]), nor P.Tannery's well-known anticipatory undoing [Heath 1913 p.315] of JB's attestation-complaint — a quibble which avoids facing the reality that there has long been no serious doubt that Aristarchos used a Great Year of 2434y or 4868y, which DR showed (DIO 11.1 [2002] ‡1 §A [pp.6-7]) leads mathematically — using JB's own rounding (again: gratefully praised by DR at idem) — to the precise “Babylonian” month, decades before any extant record of it in Babylon. However, on the positive side: JB was generously supportive of inviting DR to the British Museum conference, where DR's 2001/6/27 talk launched his Aristarchan 4868y Great Year cycle solution to Babylon's monthlength.]
    [b] We now toss at Muffiosi a question its Lunar-4&6 wing has never faced — if this cult has even thought of it: can one discover (except by the 345y eclipse cycle) how ancients pinned-down and settled-upon the wonderfully accurate period-relation 251u = 269v, by contrast to the very-VERY-nearby (actually bracketing) period-relations 237u = 254v or 265u = 284v, whose anomalistic speeds differ from the 251u relation's by only 1 part in ordmag 100,000?!
    [There's no record that any ancient realized that 355/113 is a better approximation to π (good to 1 part in better than 10 million) than Almajest 1.11's 377/120. (The two values are relatively further apart than the cited lunar ratios surrounding 251u/269v.).]
    JB (still p.124) ascribes this scalpel-like precision to sinuous but (to quote Animal House's Dean Wormer) double-secret Babylonian analyses of Lunar Four data — a process so shaky (connectively & empirically) that laborious ultra-massive data-processing must be hypothesized. (Britton loc cit; note p.125: “considerable averaging must have played a role”. Classic Emperor-of-China folly.) JB even contends that the relation's accuracy is evidence for use of Lunar Four analyses. (As if such an approach is scalpelly superior to using the centuries-long 4267u = 4573v eclipse cycle?) All this, even though JB (now) simultaneously agrees (still p.124) that the Bab.mo. came from that very cycle which includes discovery of 251u = 269v (from division by 17).
    [c] Thus, taking his grouplet's dreamed-up non-eclipse methods as an Expert conclusion (though no fundamental astronomer's support is cited), JB continues privately to replace demonstration with scorn, since he can find no mathematical fault with DR's 2002-2003 eclipse-cycle solutions to the parallel problem of the other period-relations considered here. Where is the detailed math of Britton's alternate explanation for their remarkable accuracy? (DR has here provided his simple math in detail.) And where do Babylonian records testify to use of his group's proposed bizarre methods for finding lunar orbital elements? How is it that neither Ptolemy nor Geminos nor Babylonians nor anyone else in antiquity left the slightest record of use of these schemes? As repeatedly noted here, Ptolemy provides a method for elementary use of eclipse-cycle bases (i.e., the very theory we are proposing, to explain ancients' adopted lunar speeds — both anomalistic and draconitic), so: where is the parallel Babylonian testimony to Lunar-Four inductions of lunar period-relations — accurate to 1 part in ordmag 1,000,000? (I.e., silence on Babylonianists' fantasized methods is not just Greek.)
    And (Muffiosi, are you sitting down?): HOW COULD LUNAR-FOUR ANALYSES FIND A DRACONITIC PERIOD-RELATION AT ALL? — much less to 1 part in ordmag 10,000,000?
    [Lunar-four data of course have nothing whatever to do with eclipses. This point parallels R.Newton's comment on laborious Muffia attempts to explain-away Ptolemy's solar fakes by assuming (against the testimony of Almajest 1.12) that the equinoxes were made on a krikos: a krikos is for equinoctial but not solstitial observations, yet Ptolemy's SSolstice “observation” was just as fraudulently accordant with Hipparchos' solar data as his equinox “observation”. In each case (Britton's speculations & defenses of Ptolemy's solar data — Britton, ironically, being the only Muffioso commenting on the latter without making a fool of himself): the Muffia theory is not only baselessly speculative, it doesn't even cover all the outstanding problems — while the hated, proscribed competing theory (cycles for luni-solar period-relations, or fraud for solar data) does coherently solve ALL said problems.]

  • The rock-base mental blocks preventing Muffia&co acceptance of DR's solution are pretty obvious.
    [a] We note first that the three-eclipse-cycles solution (to the mystery of super-accurate ancient lunar speeds) discussed here was not thought-of earlier by Muffiosi and rejected for cause. No, these sadly limited volk (while proposing wildly unsupported speculations of their own) never even thought of an eclipse-cycle explanation for system A, or the Hipparchos draconitic cycle, or Ptolemy's final equation — and never checked to find out whether it would work. (Since DR's 2002-3 publication of such solutions, no one has found any eclipse cycles other than those he cited, which would explain the lunar relations they perfectly solve. So: silence. Such generosity of spirit.)
    [b] And, beyond cultism: once a problem is solved, it's no longer available as a money-cow. So there is a simple economic motive for not admitting that anything in the field has been solved. (Even one of DR's associates has explicitly claimed that nothing is ever proved.) But as DR has repeatedly asked (DIO 4.3 [1994] ‡14 [p.119] and DIO 7.1 [1997] ‡5 n.40 [p.33]): “if even the most logically & evidentially one-sided controversies are to be decreed (e.g, by N.Swerdlow DIO 2.3 [1992] ‡8 §§C20&C25 [pp.109&111]) as indefinitely irresolvable, then — why investigate anything?”

    Appendix 2. Table-Flip's Elementary Consistency with Hipparchan Use of 13th Century BC Eclipses

  • As noted at DIO 1.3 [1991] n.211, Neugebauer & Toomer rightly regard Pliny's comment on Hipparchos' 600y of eclipse “predictions” as Pliny's misunderstanding of Hipparchos eclipse calculations going not forward but backward — to Nabonassar 1 (−746/2/26 Alexandria Apparent Noon). Pliny's testimony is valuable as indicating that the Almajest 3.2 table of mean solar longitude f, with Nab 1 (600y before Hipparchos) as zero-year, is that of Hipparchos.

  • It is obvious from Almajest 3.1 that young Hipparchos used as epoch “the death of Alexander” (likely adopted from Kallippos), Philip 1 Thoth 1 Alexandria Apparent Noon (−323/11/12 Julian). (Notice the alternate interpretation at Neugebauer HAMA p.307.) So Adolphe Rome reasonably suggested (idem) that establishment of the epoch Nabonassar 1 occurred during Hipparchos' career, when he created the Almajest 3.2 solar tables.

  • But: WHY Nabonassar? Some have assumed (HAMA p.608) that the choice was related to the antiquity of surviving eclipse records. But there is no surviving hint that any important astronomical event occurred during Nabonassar's reign. The oldest record Ptolemy cites (Almajest 4.6&9 and 6.9) is from the reign of the 4th king down from Nabonassar in the Canon of Kings (5th king listed at Toomer 1984 p.11).

  • Since ancient scientists were addicted to round numbers (DIO 1.3 [1991] § [p.]; DIO 14 [2008] ‡1 § [p.]), it is tempting to suppose that a complete explanation is that Hipparchos chose to go back about 6 centuries from his −145 PH-orbit epoch. And −145 − 600y = −745. The nearest regnal year to that was Nab 1 (−745/2/26.).

  • Giving Kept Rabbots a New Destructive Opportunity:
    A reasonable theory. But should our investigation end with this? Does the theory account for all mysteries here? E.g., we know (above) that planetary observations from the 9th century BC survived at least as late as the 2nd century AD. How does a theory of 600y-tables back only to 747BC comport with that reality? Or with our triple-finding that classical-era astronomical period-relations were found via use of 13th century BC eclipse observations? Those Muffia-troughing rabbots who earn their kepthood by nay-jerk-pulling the automatic-eject lever for such obviously valid discoveries from outlanders are bound to ask: if Hipparchos really computed his draconitic period-relation using a 13th century BC eclipse report, why didn't he create tables 1200y long instead of just 600y?

    The surprise answer to the question is:

    HE DID.

    This reality has lain-plain before our eyes for thousands of years: Hipparchos' Pliny-attested 600y table was actually good for 1200y — by the elementary expedient of using the 600y table in both directions.
    This suggests a (very tentative) theory: that Nab 1 was chosen as Hipparchos' tabular zero-year because it was half-way between his era and the earliest available Babylonian eclipses, c.1350 BC.
    [The fact that the king-list (Toomer 1984 p.11) starts with Nabonassar (mentioning no rulers prior to him) suggests that either Hipparchos never calculated anything prior to Nab 1 or that it originated with or passed through a party that did not know of his pre-747 BC research and-or the Hipparchos tables' reflectivity.]

  • Let's test-explore this ultra-elementary revelation of table-inversion by using Hipparchos' original mean solar motion 600y table, exactly preserved at Almajest 3.2 (with its later expansion [idem] to 800y, taking it 200y into Hipparchos' future). The mean longitude at epoch is 330°45'. So for post-Nab 1, we ADD to 330°45' the tabular longitude for the time-interval SINCE Nab 1; and for pre-Nab 1, we SUBTRACT from 330°45' the tabular longitude for the time-interval PRIOR to Nab 1. Thus, unless one finds subtraction tougher than addition, the table will yield a mean solar longitude for hundreds of years before Nab 1 just as easily as for hundreds of years after Nab 1.

  • The table breaks the interval into spans of 18 Egyptian years (6570d for each such span), single Egyptian years (365d each), Egyptian months (30d each), as well as days & hours. Alexandria local time differs less than 2 time-minutes from local time at Lindos, Hipparchos' observational home-base (DIO 4.1 [1994] ‡3 §G3 [p.46]), which he based his tables on.

  • All three eclipses Hipparchus used for finding his two ratios (716u/777w & 5458u/5923w) for the draconitic motion of the Moon were near-apsidal, and were of course partial (with semi-duration ordmag 1 hour). Rounding to integral hours and following Hipparchos (DIO 16 [2009] ‡1 n.10 [p.6]) in ignoring the Equation of Time — whose effect on solar places is trivial anyway — these are the eclipses:
    −140/1/27 22h near-perigee
    −719/3/8 23h near-apogee
    −1244/11/13 16h near-apogee.

  • The −140/1/27 eclipse observed by Hipparchos at Lindos was 221311d10h after Nab 1. To conveniently enter and extract data from the Hipparchos mean Sun tables, we (using superscript E for Egyptian years) break this interval TH into sub-intervals of time for which the tables explicitly supply solar longitudinal arcs:

    TH = 594E + 12E + 120d + 1d + 10h

    We then simply (and we mean simply — this is astrologer-level math) read directly in the table (where we round to 1'), for each of these sub-intervals, the corresponding longitude arcs. These we merely add, in the following equation (where the corresponding time-sub-intervals are in parentheses), to the mean-longitude-at-epoch 330°45' (Almajest 3.2), to learn the Sun's mean longitude f at the time of the −140/1/27 eclipse:

    fH = 330°45' + 215°35' (594E) + 357°05' (12E) + 118°17' (120d) + 0°59' (1d) + 0°25' (10h) = 303°06'

    We again emphasize the ultra-convenience that every component of the foregoing equation is provided explicitly in Hipparchos' table, as those who consult it at Almajest 3.2 will see for themselves. (I.e., no need for interpolation unless computing with T precise to time-minutes — needless for solar position.) Since Hipparchos' equation of center is +2°04' at this f, we have his longitude for mid-eclipse: 305°10'. Almajest 6.5 has true longitude 305°08' which is close enough agreement considering all parties' roundings. [Note: the next two solar longitudes we are about to compute are several degrees discrepant vs modern values, unless one accounts for the large error in Hipparchos' precession.]

  • The Babylon −719/3/8 eclipse was 9872d11h after Nab 1, an interval TF which we break into:

    TF = 18E + 9E + 17d + 11h

  • Proceeding as before, we have:

    fF = 330°45' + 355°37' (18E) + 357°49' (9E) + 16°45' (17d) +27' (11h) = 341°23'

    Given Hipparchos' +2°22' equation of center here, we have his longitude for mid-eclipse: 343°45'. Almajest 4.6 renders the same result as 343°3/4.

  • The Babylon moonrise −1244/11/13 eclipse was 181633d20h before Nab 1, or equivalently −181634d + 4h “after” Nab 1, an interval we render:

    TD = −504E + 6E + 120d + 16d + 4h

    Computing as before:

    fD = 330°45' −237°28' (−504E) + 358°32' (6E) + 118°17' (120d) + 15°46' (16d) + 0°10' (4h) = 226°02'.

    [If one just eyeballs +122°32' from the 504E entry, the above calculation can then be done purely additively, like the previous two.]

    Hipparchos' −50' equation of center then provides his longitude for mid-eclipse: 225°12'. This completes our illustration of tabular-reflection's simplicity: the Hipparchos tables can be used going backwards from Nab 1 just as easily as forwards from there.

  • The −1244 eclipse may have been chosen by Hipparchos partly because, presuming the Babylonian record mentioned that the eclipse ended near moonrise, this gave a time of day that was accurate enough for his purposes. (An ordmag 1 hour error would have minuscule effect on the deduced mean lunar motion.) If the reality of the Babylon −1244 eclipse record becomes understood in academe, it will contribute to modern knowledge by setting an upper limit on ΔT for that remote date.

    Appendix 3. Summary of Exploratory Research Results.

  • Summarizing what we have available supporting the reality of pre-Nab 1 Babylonian celestial observations:
    [1] Sidereal period-relations back to at least to 850 BC.
    [2] Geminos' knowledge in the 1st century BC of the 800y eclipse cycle.
    [3] Use of 13th century BC eclipses to solve all three of the only hitherto-mysterious four-digit numerator&denominator lunar period-relations — not one of which had ever previously (nor subsequently) been mathematically traced by modern academe — before DIO (2002-2003) produced twenty-four exact hits on all twenty-four digits. Check out above for every one of the twenty-four. All three solutions are by attested method and unique pairings and eclipse intervals.
    [By unique and non-arbitrary, we mean: in the dozen years since publication, none of DIO's cultist non-appreciators has been able to find a single miscalculation, invisible eclipse, or alternate eclipse-pairing. Or attestation for any other method. Or even speculation of a sensible method that could account for the 4-digit ratios in which these ancient mean motions are expressed. Or account for all three relations' remarkable accuracy: 1 part in a ordmag a million. Even closer in the draconitic case.]
    [4] Long before DIO's findings, the History of Science Society's house journal Isis published the estimate that Babylonian celestial observations were alive c.1350BC.
    [5] This figure is consistent with a reasonable interpretation of Pliny's testimony connecting Hipparchos to a 600y span, presumably that of the original 18-year-interval table for his eclipse research, a table of which our reflective flip showed was actually good for 1200y years back from 145 BC or 600y back from Nab 1 — i.e., c.1350 BC.
    [6] Recall also our novel if explicitly speculative hypothesis that Hipparchos' choice of Nab 1 as his tables' zero-epoch might have occurred because Nab 1 was half-way between 1350BC and his own 145BC time — the seam of his folded 1200y table — allowing him the luxury of efficient back-calculation of any eclipse in that 1200y range.

  • The foregoing items vary in strength but they are consistent with the DIO hypothesis that usable Babylonian astronomical observations from as early as the 14th-13th century BC were made & preserved (probably for superstitious reasons, ironically!) — and were much later known to and profitably exploited by mathematically able classical-era Greek scientists, to establish astonishingly accurate pioneering estimates of celestial motions — the earliest instance in all history of precise predictivity and technology, the hallmark of high science.

    DIO thanks Peter Nochold for spotting and correcting a confusing misprint in the original posting.

    [Intermittent revisions 2007/12/23-2015/1/1.]