A friend wished to program his rotary table, so he could photo' the moon
over time w/ its position in the focal plane constant and supplied me w/
the Navy's moon rise table. He wondered about the variation. I do
also. I plotted the cumulative moon rise time and the differences. It
has a 3% variation (+/- from the mean). The variation has two periods
* one about 27 days (not surprising), and another of about ten days w/
about one third the amplitude.