The Dresden Codex Eclipse Table

The primary basis for our understanding of eclipses as viewed by the Mayas is the eclipse table of the Dresden codex. This consists of a series of 69 intervals, mostly of 177 days, some of 178 days, and 10 of 148 days, accompanied by cumulative totals and by a list of days reached by the intervals over a 3-day range for each interval. Each interval is accompanied by a very short text, largely undeciphered. The table is interrupted by 10 pictures, each following a rare interval of 148 days. Longer texts occur with pictures, frequently mentioning eclipses of both Sun and Moon. The Mayan astronomers seem to have been particularly interested in the months when the instant of new Moon shifts from the node enough so that there are successive eclipses of both Sun and Moon in a single month.8 The glyphs for eclipses were first recognized in these texts. The pictures normally show deities who are associated with the dates. The total length of the table is 11960 days,

8 Recall from §5.2.1 that eclipses occur when the Moon and Sun are within certain limits of a node—a crossover of the lunar orbit and the ecliptic. On rare occasions, an eclipse can occur within about a month of a previous one because the Sun moves slightly less than 30° over a synodic month and the major ecliptic limits can be as large as ±18.5° for partial solar eclipses.

which is a good cycle for the return of eclipses to the same place (in Table 5.4, Cycles 1 + 4). This interval also restores the same day of the 260-day cycle. The 11,960-day interval represents 32 tropical years (hereafter abbreviated simply as Ty) and 272 days, approximately 3/4 of a year. Table 12.9 shows a transcription of the positions of the eclipse table, counted from the base 9.16.4.10.8 12 Lamat 1 Muan with Long Count and month positions added and only the middle date of the 3-day range given.

Preceding the eclipse table proper are a number of calculations that can be used to reach true dates from the table dates (in DHK's interpretation) or to correct the table and furnish revised bases in a related but slightly different view (more widely held). The base parameter is defined by a date that is eight days after the Maya era base at (13/0).0.0.0.8 12 Lamat 16 Cumku, an apparent equivalent of the Ring Numbers of other tables (see Table 12.8) and by the previously mentioned 9.16.4.10.8 12 Lamat 1 Muan, an interval of 1,412,840 days.

Until recently, it has been generally assumed that such table bases as 9.16.4.10.8 12 Lamat 1 Muan as the base of the eclipse table or 9.9.9.16.0 1 Ahau 18 Kayab as the base of the Venus table were intended to reach real phenomena contemporary with the indicated dates. In the case of the eclipse table, this accorded so ill with the Thompson correlation that it was suggested that the table should be divorced from the Long Count base that immediately preceded it. A study of the placement of the 148-day intervals in the table by Teeple (1930) indicated that the base of the table should be within a day of a node passage of the Sun (probably the day after). In the Thompson correlation, this was far from being true for 9.16.4.10.8 12 Lamat 1 Muan, and it was suggested that the "real" base was an unmentioned day 12 Lamat, much later. Recently, Bricker and Bricker (1983) have suggested that the table is a "floating" ideal table, designed to be entered through various corrections, accepting 9.16.4.10.8 12 Lamat 1 Muan as the base of the table, but denying Teeple's structural argument (from the placement of the 148-day intervals) that the base was near the instant of a draconitic node passage. Kelley (1981,1987) has developed new evidence that the table was a structural reality not originally designed to function at the table base. Kelley (1980) had suggested that the date 9.16.4.10.8 12 Lamat 1 Muan had originally been calculated as a Classic Period counterpart of a date 12.10.12.4.8 12 Lamat 1 Muan (before the normal Maya era base), which was exactly 11,960 days or one eclipse table length after 12.8.19.0.8 12 Lamat 1 Pop, a Maya New Year's day. The latter is the date from which, Kelley argued, the birth dates of the gods were calculated. This day, 12 Lamat or 12 Rabbit, was postulated by Caso as the name of an old Moon god of central Mexico, and supposed by Kelley to have been the eclipse cycle god. In Kelley (1980), no effort was made to determine the precise structural nature of the relationship between 12.10.12.4.8 12 Lamat 1 Muan and 9.16.4.10.8 12 Lamat 1 Muan. The possibility of the use of a formal table of 11,960 days, used without correction in order to measure the degree of variation of the real phenomena led to fuller examination of the dates. The least-common denominator of the 11,960-day cycle of eclipses and the 18,980-day calendar round is

873,080 days (46 calendar rounds or 73 eclipse table periods constituting 2392 Mesoamerican years). Such dates, counted from the presumed early base, occurred twice in the pre-Classic Period and then leaped the entire Classic Period (of about 600 years, missing about 12 dates 12 Lamat 1 Muan).

It was then realized that one other date in the table was a day 12 Lamat within the 3-day variation allowed by the table, at the important interval of 9360 days (in Table 5.4, Cycle 1 + 2 x Cycle 2) reaching 12.11.18.4.8 12 Lamat 11 Mol. If one counted from this as the base by multiples of 11960 days and went forward to a 12 Lamat 1 Muan date, the first occurrence of such a date would have been at 3.14.19.6.8 12 Lamat 1 Muan. From this, one interval of 46 calendar rounds (as above) goes forward precisely to 9.16.4.10.8 12 Lamat 1 Muan (see Table 12.10).

This affords strong evidence supporting the placement of a "proto-base" by the Mayas at 12.10.12.4.8 12 Lamat 1 Muan and equally strong evidence that the late base of the eclipse table would have differed both on the true date of a draconitic node passage and on the correspondence with true lunations, depending on how much error the Mayas had in the parameters used in calculating the early base. In effect, this interpretation means that the eclipse table can offer no guidance in solving the correlation problem, except in that it suggests that other tables may have been structured in the same way.

The same calendar round date, 12 Lamat 1 Muan (±1 day), also has an important placement in real time in the intertribal tzolkin as an annular solar eclipse with path of cen-trality nearly across the Maya site of Copan, in Honduras, at J.D. 1 446 712, -752 (753 b.c.) November 18 (in the Julian Calendar), as given in Oppolzer. This was first pointed out by Spinden (1930, pp. 55-56). However, by more recent calculation, the track is markedly farther south. The implications of this date have not been considered adequately by anyone. Minimally, this implies either that the Mayas were already using the full calendar round in 753 b.c. and recording eclipses in it or that they were able to back-calculate eclipses with great accuracy and did so, using this date to place the intertribal tzolkin in step with real time. The latter could have been accomplished either at the time of invention (if there was no calendar correction) or at the time of a calendar correction if one did occur. It seems unlikely, although far from impossible, that the calendar was in use for more than 700 years (even in the Spinden correlation) with no use in a known inscription. At the same time, most Mayanists would be equally unwilling to admit that the Mayas could have retrodicted9 a locally visible eclipse at the time of the inauguration of the calendar. It is even more unlikely that this is a structural reality of a purely accidental nature.

In the Spinden correlation, this date is 24 calendar rounds before 9.16.4.10.8, an interval of no known significance. In the Thompson correlations, the date would have been one day either before or after 5.19.15.11.8 12 Lamat 1 Muan, which is 29 CR before 9.16.4.10.8. In this interval, the

9 This is an archeological term meaning the equivalent for the past to predict for the future. In this case, the term back-calculate is a clumsy equivalent.

Table 12.9. Potential dates of eclipses from the Dresden eclipse table.

Dresden lunar table: Calculated to middle line of table Notes

Table 12.9. Potential dates of eclipses from the Dresden eclipse table.

Dresden lunar table: Calculated to middle line of table Notes

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