Archaeoastronomy tools
Declination calculatorThis 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.). |
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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 on this site
A few old programs, including the original GETDEC program, can still be found among archival resources held here on a back-up server at Leicester University. These include
- Horizon finder, a program by David Dearborn to scan an image and produce a digitised and calibrated horizon profile
- Pohualli, a Mesoamerican calendar conversion program by Arkadiusz Soltysiak and Arnold Lebeuf
Others 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 For example, GRIDLA and LAGRID have been superseded by several tools available on the web, such as (for the British National Grid) the Ordnance Survey’s Co-ordinate calculation spreadsheet.