Hi Mark, Dave, Patrick and Tony: Thank you all so much for your detailed answers to my questions. It seems that every time I ask the sundial group what I think to be a simple question with a clear and simple answer, the answers always turn out to be anything but simple and clear cut But this is how we learn. (When your answers turn out to be complicated, at least I don't feel embarassed about having asked a revealingly stupid question!)
Tony, the EOT poem is great for people with better memories than mine; as I can't even remember a good joke when I hear it. So I use a different method for determining EOT values in my head using visualization: Knowing the general shape of the EOT curve, the days when EOT=0, and the dates when EOT is maximum and minimum and these values, it is very easy for me to mentally guesstimate approximate EOT values for other dates in-between the known dates. You could improve this mental picture of the curve if you also memorize the dates of the sub-minimum and sub-maximum EOT values (May 15, EOT=-5 and Aug 1, EOT= +7) John
