DescriptionSol Et Umbra is a program that shows sun ephemeris and is devoted to sundial designers.
The program shows the main sun parameters for the actual (or whichever desired) time and date:
- latitude and longitude
- right ascension and declination
- local azimuth and height
- equation of time
- local or time zone sun time
- local or time zone mean time
- time of rise, set and transit (local noon)
- total number of hours of light
When a network connection is available, by means of the Network Time Protocol the time error between the phone clock and an atomic clock is found and used to correct the displayed time.
The position of the device is found through GPS or, when this is not available, through information from the network or finally through manual setting.
Moreover Sol Et Umbra shows the time using the following time systems:
- italic time
- babilonic time
- temporal time
Sol Et Umbra uses the orientation sensors available in the device in order to compute and show the time lines of a sundial designed on the plane of the display.
The graph is updated after any movement of the device.
Finally the program can show the lighting conditions of the dial as drawn on the device plane by means of an azimut/height graph that shows for any day in the year and for any hour in the day whenthe dial is lighted.
The accuracy in the measurement of the orientation of the device depends on the accuracy of internal sensors. Moreover in the presence of external magnetic fields the declination and inclination as shown by the app can have a large error. If you plan to design a sundial do not rely on these numbers, please use the measurement methods described in the author's site.
Sol Et Umbra needs the following permissions:
- network connession for clok sync (if not available, a smaller time accuracy will be obtained)
- GPS localization (if not available, the current position must be manually introduced)
More information on the program are available from the author's site:
From this same site a complete free program for sundial design and simulation is available (Windows only).
Author can be contacted at the address: