A software developer in Berlin has come up with a very useful set of
information for the keen diallist. It is called LunaSolCal and gives details
for the sun and moon. For the sun it gives (longitude corrected) the time of
solar noon, the equation of time, azimuth at sunrise and sunset, length of day,
declination and the times for the different definitions of twilight. Equivalent
information for the moon is given, complete with an image of the current phase.
A second page gives graphical illustrations of the tracks of the sun and moon.
The third page gives a summary of the day parameters such as sunrise, sunset,
time of solar noon and the length of the day, with similar details for the
moon. Finally a page gives the precise times of the equinoxes and solstices.
Like all of these apps, the dates can be changed. Credit is given to Meeus and
Duffett-Smith for the algorithms. The relevant website is www.vvse.com and the
cost £1.49. The app works nicely on my iPad and the website implies that it
will work on other platforms. Having given personal 'ratings' for other apps,
this one does not have the pictorial glamour of some, but has much useful
technical information in a very handy format, therefore 8/10.
The British Sundial Society webmaster has taken the initiative to add my notes
and others, together with some images, to the website so that a convenient
summary of apps useful to sundiallers is available.
Merry Christmas and a Happy New Year, Doug
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