Dear Frank,
Yes, the width of the shadow of a round rod polos with 0.5" in diameter is not always the same. I realized this not before 2009 when I was already engaged in sundials for at least 25 years!
The figure shows the width w without penumbra on a horizontal dial as function of the hour angle t for the latitudes 0°, 15°,...,75°,90°.
Best wishes
Rolf Wieland
Rolf Wieland
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
