This large clonglomerate stone sits just off center within the henge. The first report I read of this site said it was a large slab, but it doesn't really fit into my defintion of a slab.
It is about 2.2m tall and 1.2m wide at the broadest point. There are several natural solution pits in its surface near the base on the east side.
From Borris in Ossory take the R435 south. Take the first right (3km) and take the right fork at the next junction. Continue until you reach an odd fourway junction. Behind the hedge directly in front of you there is the henge. Go left and park up. Walk through into the field and up into the henge to get to the stone.
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.