Pop- up glossary and paragraph links. Move mouse over text in this colour and Click

Gorslydan

The Megalithic Calendar alignment from S1 to Gorslydan, Llanbister, Mid- Powys

06:37, 15th October 1997. Declination -8*32.4'

06:37 15th October 1993. Declination -8*34'

06:42 25th February 1995. Declination -9*17.4; one day before required declination.

W/7.4.1            These photographs were taken on or near a day when the Sun approached the declination for the 10th and 16th Megalithic Calendar Intervals. W/7.4.2            From good photographs taken in different seasons and years a computer aided survey can be made to establish the true declination of a foresight. W/7.4.3  Gorslydan carries two typical earth tumuli which bracket or frame the lower limb of the rising sun on the first days of two Megalithic Calendar dates, nos: 10 & 16 -in the Gregorian calendar 15th October and 26th February.

W/7.4.4  Effects of air temperature on the apparent declination of a foresight.            With data of this precision we might examine a further very slight difference from the ideal discernable in these photographs. The effect of air temperature upon an observation requires an adjustment of  0.1 arc minutes per 1 degree Celsius. It is thought that Bronze Age Britain might have been some 5 degrees warmer on average than today which would require an 0.5 arc minute correction. The effect of this would be to lower (apparently) the hill line. This would bring the midpoint of the foresight, between the two tumuli, into closer agreement with the lower limb of the Sun at the ideal position for these calendar divisions.

Pop- up glossary and paragraph links. Move mouse over text in this colour and Click

	<<<Back

with comments or queries- powys@megalithicsites.co.uk