NMRS record no. HY21SE 19 is a small mound of earth and stones on the SE slope of the hill between the Ring of brodgar and Bookan farm which has/had a stone setting around the base. Its present dimensions of ~8m diameter by 0.6m high accords well with those of 27' diameter and 18" high reported in 1946, meaning little or no erosion has happened since.
It can be seen by the northern fence of the field that also holds the Wasbister 'disc barrow' and the Bookan Cairn settlement (as well as a possible burnt mound by the pow/lochan). From below it appears as a bright green grassy mound on the hill's SE slope skyline. Only a few yards away is a very rough mound. From some views the ragged mound is so big that this and the cairn could even possibly be a single item subjected to different fates at E and W. But I only found a single flat stone on the whole of the mound's surface. I make the cairn round with a diameter varying from 6.4-6.5m, which is several feet short of the recorded 8m/27'. Though there are some loose stones around the base there are no signs that these have ever been embedded. But even sans stone setting my eyes thought there might be a cropmark 'ring' about the cairn of roughly the right size.