Spehro Pefhany wrote:
> The position is inferred from our calendar and clock.. if that mapping
> (say the day of the year is off by a few days), then the sun won't
> quite be at the expected position. Of course there's an average of 1/2
> day absolute error anyway since we correct our calendar in increments
> of one day rather than shaving smaller bits of time.

My point was that even if you're a few weeks of whole days off within the
year, it still wouldn't matter if you're just trying to face a flat panel t=
o
the sun.  For example, the cosine of 5 degrees is still 1.00.

The apparent altitude of the sun at midday follows a sine fairly well.  It
changes most quickly each equinox and hits the peaks at the solstices.  Eve=
n
at the equinoxes, the change is less than 2.9 degrees per week.  So go ahea=
d
and be off by a week or two.  Two weeks off is less than 6 degrees error at
most.  Cosine(6 deg) =3D 99.5%.  Big deal.


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