Dear John, Your explanations sound like about the right level for a users' manual. Maybe because I'm a scientist, I think it is important to at least mention the major sources of error. In my opinion, the biggest problem is determining the exact phase of the moon by looking at it. (Of course, you can get pretty accurate by looking it up in the newspaper.) I would guess a misjudgment of the phase by up to one day is common without a lot a practice. That will result in up to 48 minutes of error. The EOT might be considered small compared to that, but I think I would mention that it should be used. Some of your users may get a kick out of an accurate measurement.
The other errors, like those due to the tilt (5 degrees) or eccentricity (0.0549) of the Moon's orbit, I expect to be on the order of the square of the parameters, which is under 1%. But 1% of what? 1% of a day is 14 minutes, so I would need to give this some more thought. As far as your eclipse observation goes, I suspect the eclipse either took place when the correction was small, or you misjudged when the center of the eclipse was. Since a lunar eclipse takes a fairly long time, the "moon time" at the start and the end can differ by several minutes. Art Carlson
