Clive Ruggles


… is the study of beliefs and practices relating to the sky in the past, especially in prehistory, and the uses to which people's know- ledge of the skies was put.


Professional bodies

Free software tools

Basic declination calculator


by Andrew Smith

See the Tools page for more info


Springer Handbook (2014):


Ocarina Books publishes and distributes books relating to archaeo- and ethnoastronomy



This list of my books and selected papers and articles contains links and downloadable copies where available.

Archaeoastronomy tools


Declination calculator

This basic declination calculator calculates the astronomical declination of any structural alignment given the true azimuth, horizon altitude, and terrestrial latitude. It applies a mean refraction correction to the observed altitude and (for geocentric lunar declinations) mean lunar parallax.


It is an interactive version of the “GETDEC” program referred to in Astronomy in Prehistoric Britain and Ireland (p. 169) with only the basic functionality included (i.e. no offsets etc.).

Horizon visualization from DTM data

Andrew Smith’s excellent “HORIZON” tool generates visualisations of horizon profiles annotated with azimuth, altitude and declination and showing rising and setting paths of the sun, moon and/or selected stars as desired.


Archival resources

Older programs mentioned in Astronomy in Prehistoric Britain and Ireland, such as the original GETDEC program, are no longer available. Most are long obsolete. For example, GRIDLA and LAGRID have been superseded by several tools available on the web, such as (for the British National Grid) the Ordnance Survey’s Co-ordinate calculations spreadsheet.

Astronomical heritage

Portal to the Heritage of Astronomy

Read more on the UNESCO–IAU Portal to the Heritage of Astronomy and about astronomical heritage in general

Free downloads

ICOMOS–IAU Thematic Studies on Astronomical Heritage

No. 1 (2010): See here for more information or click here to download a copy directly (46 Mb)

No. 2 (2017): See here for more information or click here to download a copy (19 Mb)


Astronomical World Heritage


Download a copy of an article published in A&G (Aug 2019 issue)

Stonehenge and Ancient Astronomy


Download a copy of the Royal Astronomical Society’s factsheet

Alice Ruggles Trust

If you are looking for things related to Alice and/or information about stalking, please visit the Alice Ruggles Trust website