Glossary X
At a lunar backsight where permanent or temporary ancillary extrapolation gear has been set up there should be a length preserved between major stones which is the 4G for this site. This 4G represents, on the ground, the lateral distance an observer must move in order to 'shift' the Moon through the declination range K. K is the change in the Moon´s position during the 24 hours preceding a standstill. At a Major Standstill it is 46.5 arc minutes and at a Minor Standstill 30 arc minutes. See also- K, ANGULAR DISPLACEMENT, EXTRAPOLATION PROCEDURE, LUNAR STANDSTILL.
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S2, Llananno to Warren Hill tumulus
Crown Estates, Llananno.

High precision alignment from S2 stone chair on Brondre Fawr ridge to Warren Hill tumulus indicating the upper limb of the Sun when rising on megalithic calendar intermediate intervals nos. 9.5 and 16.5.- which occur in the Gregorian calendar @ 11th March @ 3rd October.

Warren Hill Bronze Age Tumulus, Crown Estates.

Warren Hill, Llananno.
One of the high hills on the Crown Estates, Llananno. A typical Mid Wales moel-a round-topped symmetrical hill. All of the highest tops on these Crown properties are adorned with one or more earthen tumuli. The bed stone of this area is Silurian/Ordovician mud-stone and very little rock is exposed as even the highest hills have a covering of boulder clay. The only available materials for mound building is this clay and turf stripped from the nearby hill-side.
Warren Hill OS.
As with most of the tumuli groups in Llananno this tumulus is located on the exact summit of the hill.
Warren Hill tumulus sits within an arc minute of the rising point of the Sun's upper limb when it has reached the ideal declination for intermediate megalithic calendar intervals nos. 9.5 & 16.5.
The ideal declination for these dates, (-13 deg. 59.4 mins.), had been attained 47 minutes, in time, before this photograph was taken.

The Green Flash

The legendary green or emerald flash, more halogen blue in this instance, captured on the morning of the 3rd October 2001.
An accurate montage of the solar disc is placed for reference in this image. The disc is some 31.6 arc minutes in diameter. Notice how the flash appears magnified. This photo was taken only two seconds after first gleam was visible when the rim of the disc must only be a few arc seconds over the horizon- yet the green flash stands several arc minutes clear on the hill- top.

Digital Survey from a photographic series.

The series of images captured may be layered together to show the exact path of the rising Sun.
When half- risen the diameter of the disc fits exactly between the tumulus and the intersection of the hill flanks. With this arrangement estimates of the proximity of the ideal moment that the required declination had been, or would be, attained might be made.