I recently posted the stuff below on another forum and though it may be of interest here . Although it does come with a Nerd warning . Anybody wanting figures etc do ask and I'll send them on .

Stonehenge has always eclipsed (cough ) Avebury in the archaeoastronomical stakes . Much of it is contentious , with so many possible
bits and pieces to choose from you could prove anything . What is not in dispute is the axis echoed in the avenue which suggests two obvious orientations
with one coming out slightly more accurate than the other i.e. winter solstice over summer solstice .
Part of the problem with Avebury is that like Stonehenge there is so much to choose from regarding "alignnments " between stones ,compounded by possible uncertainty in relation to the re-erection of some stones .Another is the geometry , where is the centre ? Conventially alignments are considered from that point (that concept is due to mainly to Thom and relatively reasonable ,although there is no way of retrieving what ,if any , point of reference was used by the builders ) .What is needed to satisfy the demands of intentionality are outlying stones or related linear monuments associated like a cursus ,passage or avenue .Avebury has the remains of one Avenue and recent excavation has provided some evidence for the other at Beckhampton . The Kennet avenue consists of some straight sections and some of those have proved to have significant astronomical alignments , e.g. stone pairs 11-16 (the avenue is defined by paired stones ) stay on a orienation of 123.9 degrees for approx 120 metres when this is extended to the horizon it conicides with the point where the winetr minor lunar standstill will be seen every 18.6 yrs , it is also the site of Bitham barrow which is probably insignificant and fortuitous but a handy visual aid . Stone pairs 28-37 keep to a bearing of 148 degrees for a 220 metres and the point on the horizon the yindicate is the point where the major moon standstill will be seen every 18.6 years . Stones 78-83 are aligned 134 degrees and run for 110 metres they point to a point on the horizon where the winter solstice sun rises annually . There are other possible alignments relating to Beckhampton avenue but they are dependent upon the archaeological plans having an accurate northing , if it is accurate then there are alignments to winter major moon rise and set . As mentioned previously archaeoastronomy uses precise calculations , the problem is deciding whether it shows intention on behalf of the builders . Any single standing stone couild be shown to "align" to any major astro event (at the latitude of Avebury ) but there is nothing to show intention and is therefore irrefutable and not scientific at least with an avenue there is a clearly defined bearing . Whether the builders intended it to indicate the astro events is open to interpretation .