It almost tried to get past me, but thankfully it kept bothering me until I went back and took another look. A study inspired by DUNE at GHMB resulted in identifying a chain of numbers linked by 2 Pi that included both the Lunar Year AND the Eclipse Year, and today I went back and tried to take another look at it to be sure.
An incomplete rendering of the series based on the important number 1115.419204 which may have already been found at least several times in ancient American architecture. It is proposed to be included in the base footprint of the Pyramid of Niches, and may be a pyramid diagonal length at Tikal if Maler’s data on the exteriors of the Temple Pyramids, which were generally in rather rough shape at the time, can be accepted.
1115.419204 may also appear in the El Castillo Pyramid at Chichen Itza. The number has more than one geodetic property, although I’m omitting discussion of those here but some details are included in the GHMB post linked above.
Of metrological significance,
“Circumference (1115.419204 / 2 Pi^1) = Diameter 177.5244799 / 2 = Radius 88.76223994 = Lunar Leap Month x 3?
(1115.419204 / 2 Pi^2) = (1 / Lunar Year) x 10^n
(1115.419204 / 2 Pi^3) = Venus Orbital Period x 2
(1115.419204 / 2 Pi^7) = 1 / Eclipse Year”
While we may not (?) be able to comfortably identify the unit historically, a unit that is fundamental to the “Best Eclipse Year” turns out to be 2 Pi away from the Incidental Megalithic Yard, which was currently thought the limit in the expansion of a metrological unit series in 2 different directions from the Sacred Cubit.

The 2 Pi metrological series and what were previously thought to be its limits.
I have recently commented on this remarkable ability of the Sacred Cubit to host a series in either direction,
“I’m quite taken with how if you divide a Royal Cubit by a Remen, you get the amazing Megalithic Foot, one of two numbers that ancients seem to try to build into everything regardless of geography so far; if you multiply a Royal Cubit by a Remen, you get the amazing Sacred Cubit.
That much more reason for them (the Ancient Egyptians and others) to have been so stuck on the Royal Cubit and Remen, if you ask me.”

The revised series now featuring the “Eclipse Unit”.
So what we see is that even though the “Eclipse Unit” has been a rather mysterious metrological oddity because it refuses to resolve into other known units, the reason for that is apparently that it is a unit in its own right, and very closely related to most of the metrology being observed though the very same series.
This and the ability to form the “Eclipse Unit” from other metrological units (AE Megalithic Yard / Megalithic Foot x 15 = Eclipse Unit, Hashimi Cubit squared x Remen / 4 = Eclipse Unit) lend a strong sense of legitimacy to the particular unit value.
Thus we can relate the “Eclipse Unit” to other units in both of the ways identified here as best because they are exact

I still don’t know exactly what to think of the unit as – a “Eclipse Year Unit”? An “Eclipse Unit”, as David Kenworthy thinks of a similar unit value? A “Nilometer Cubit”? Perhaps its technically nothing to do with a Cubit – but we do now know more than ever that it is something, and that it is a metrological unit that belongs with the others.
Perhaps the next thing that might happen is to go back to the chambers and coffers of the Giza pyramids; awhile back I wondered out loud here what if the mystery measure of the Giza coffers and the mystery of the Nilometer Cubit were one in the same, but I haven’t actually answered the question yet. Maybe now we have more context and more confidence to facilitate that very thing.
The Eclipse Year Unit may not have been firmly identified, but it has now been certainly classified so that we can see where it fits into the scheme of things, which also means that multiple pointers point to it as legitimate.
It doesn’t seem like long ago the Hashimi Cubit (aka Pied du Roi) was going through the very same process.
I decided that before I posted this, I would briefly check and see if there is anything recognizable or worthwhile beyond the Eclipse Year Unit in the series, and in fact there is. Another 2 Pi out from the Eclipse Year, we find the Anomalistic Month value, as we seem to have recently displayed in one of the Mayan “altars”.
Since it registers this way as a value with a seemingly unique base unit, we presume such a unit would be required for the expression of the standard Anomalistic Month value; thus it may require christening to the effect of the “The Anomalistic Month Unit”.
The diagram now looks like this

So, we now have a total of nine ancient units of measure directly linked in series by 2 Pi, plus we have what appears to be a total of 5 units based on and linked by Pi^n.

The currently known metrological unit values based on a valid whole number and Pi^n.
Thankfully, we now seem to know more about these units and the corresponding astronomical values they embody, and how to get from one to the other using 2 Pi.
The calendar stone from Ucanal with a projected radius of 27.55182815 / 10 ft, especially being a circle “calling for” 2 Pi, is presumably able to communicate a rather wide range of astronomical constants from a single series, as would be the other calendar stones by the same account.
This is of course not limited to ancient American calendar stones, it no doubt also applies to ancient architecture elsewhere.
Consider this observation: 360 / 27.55182815 = Sunhoney Number / 2.
The Anomalistic Month Unit or its equivalent would seemingly be also required to metrologically define the suggested measurement values for the Sunhoney Stone Circle, so we can already point to what may be at least one example of the Anomalistic Month Unit in actual use in Megalithic design.
–Luke Piwalker