If you move a bit from the centre in any direction the phenomenon will still be much the same . It's the recumbent as a whole that is the "screen" and a small unseen spot on the outside of the recumbent has no impact orientationwise .
Even though the marks are not visible to the observer as they are, it seems they chose to put them in a certain place, that being the area of the moonset?
I have visited, but can't remember, whereabouts is the cist?
Just posting this again in case it was missed :
Its summit [the recumbent] is relatively even, rising gently towards the E, and on the outer face there are at least two possible cupmarks, situated to the W of the natural indentations known as The Devil’s Hoofmarks
(Canmore)
So genuine(?) cupmarks on the outer face, as well as the natural marks?
Also, if we are talking 'drama' (and who can say we aren't?) it could be aan area for a person or persons to stand, perhaps to be illuminated at that moonset time, 'callanish' style.
Fanciful, that one, I grant you!
There was a roughly central ring cairn . There is a slab of rock in the middle but whether prehistoric ? , possibly not .
There are examples of rock art and cup marks on recumbents no doubt about that ,those at Cothiemuir are "possibles " i.e. not that convincing/difficult to be sure .
Drama , why not . But when you think of other monumnets that have astro alignments like passage graves , punters in the passage acting dramatically or even being there is unlikely , maybe what matters is the alignment itself .
A great subject though. I'd like to look a little deeper into alignments. Do you know of a good site/software for azimuths/declination and general info? Do you use landranger maps to calculate yr declinations for rising/setting sun, for example?
Bear with me here, but if i'm looking along one stone, an outlier for arguments sake, to another, say NW, I guess its a compass bearing, then checking the horizon height via maps? And once you have that, using it to get the declination of (for this example) the rising sun at that point?
If youre willing to share a bit of info on methods, i'm listening!
One difficulty is understanding the concept of declination ,if you already do so then that's a big step forward .
Burl , Ruggles and Thom all used maps for their calc at many sites , not all by any means , others were surveyed in the field , but there are problems relying solely on maps e.g. grid north is not true north etc .
Having said that we are not dealing wih extreme accuracy in the sites so being a little out might not hurt but we should attempt to be as accurate as possible at our end of the calc .
Basically get an accurate as possible alignment between the two markers , compass is ok but in some respects not as good as a large scale map , if the markesr are visible on GE even better . The accuracy will depend on how close the two ppoints are to each other ,if they are close say 2-10 metres apart there is much more room for error i.e. width of the markers etc ,the greater the distance the greater the accuracy . Then as you say continue to the horizon then calculate the alt from the site to the horizon and include in the dec formula , including refraction and parallax (only for the moon ) to provide a more accurate figure . If tht doesn't make sense , do ask and i'll re-explain.
Was that a Fraserian "I'm listening " ?
