Instrumental errors may be specified for high-precision work.
Ephemeris data are required in order to calculate the sun's azimuth at a given time.
Site co-ordinates may be specified either using latitude and longitude or the British or Irish National Grid. NGR co-ordinates are required in all-figure form (i.e. an integer in metres, with the leading 100km figure included).
Angles may be entered in a variety of formats.
Click here to download the program. NB When downloaded, you will need to change the file name from stimes.exe to stimes.com.
Values of the sun's azimuth as viewed from a given location at a given time can be also obtained directly using a Web-based ephemeris such as NASA's Horizons (JPL on-line ephemerides). Enter lat and long of location, time (e.g. 1 minute intervals while sun readings were being taken). The on-line system will generate apparent azimuth and altitude (they call it elevation using the opposite convention to that used here and in Astronomy in Prehistoric Britain and Ireland) and angular diameter. Extrapolate between the minutes to get the azimuth for the nearest second of time if needed.
Author: Clive Ruggles