NavList:

Fred Hebard, sorry to take a while getting back to you on this. You wrote:

"I'd like to believe you, but show us the data.  Alex has very fine 
data and a good sextant.  I've done OK, but not 0.1'. "

 

I've posted lots of data over the past few years. But to me, the most important evidence I have seen was during a group lunars session at Mystic about a year ago (we were largely clouded out in June this year). The majority of our group shot lunar distances accurate to +/-0.1 minutes of arc on the first try. One person in particular had an error of 0.0, and this was the first time he had picked up a sextant. It is important to note that the I.C. in this case had been previously determined; that is a major factor in getting good lunar distance observations. When I see five people in a row measure lunar distances to +/- 0.1 minutes of arc (and I just double-checked my notes from last September), that's pretty convincing evidence! Two people in the group had lower accuracy results. In one of those two cases, we all tried his sextant and got consistently bad results. It's not the observer --it's the sextant.

 

As for Alex's sights, I don't dispute them one bit. They represent one observer with one sextant though. No more, no less. You also say that he has a "good sextant". How do you know? Seriously, if a sextant has significant arc error at the level of, say, 0.5 minutes of arc or less, how can you find out? Of course Alex had his tested, but the results were simply "nil" which means they were below the ability of the testers to detect reliably. I now have Alex's sextant here in Chicago. He asked me to try it out and see if I can get better results with it or confirm his inconsistent results. We'll see... but not unless the weather cooperates. It has been "unpleasant" weather this week in Chicago: we had our first snow shower of the season last night.