I have seen many images of this site and each has confused me. Most of them show the four huge stones that stand on the east side of the monument. Others show the pile of stones in its centre or the smaller standing stones on the west side. Having now visited the site I am still a little confused.
I can only assume that it was once a smaller version of Beltany Tops (County Donegal) - a cairn with standing stones around its circumference.
The four stones mentioned above are around two metres tall. One of them has a lump at the top that sticks out of one side. It is this stone that makes photos of this site so easy to identify. The stones on the west side are smaller, not reaching higher than 1.5m.
The site's views are all westward, as it is located on the west-facing slopes of a low hill known as Mass Hill. Were masses held here while Catholicism was banned? Sadly the views are now much interupted by pine trees and houses, but they would have been extensive as the land to the west is very open and flat.
This is an explanation of (and a bit of a disclaimer for) the coordinates I provide.
Where a GPS figure is given this is the master for all other coordinates. According to my Garmin these are quite accurate.
Where there is no GPS figure the 6 figure grid reference is master for the others. This may not be very accurate as it could have come from the OS maps and could have been read by eye. Consequently, all other cordinates are going to have inaccuracies.
The calculation of Longitude and Latitude uses an algorithm that is not 100% accurate. The long/lat figures are used as a basis for calculating the UTM & ITM coordinates. Consequently, UTM & ITM coordinates are slightly out.
UTM is a global coordinate system - Universal Transverse Mercator - that is at the core of the GPS system.
ITM is the new coordinate system - Irish Transverse Mercator - that is more accurate and more GPS friendly than the Irish Grid Reference system. This will be used on the next generation of Irish OS maps.