NavList:

Dear Fred,

Thanks a lot for you help. I think I have to worry the next months more about my practice to take sights than about non correctable errors of my sextant ;-). With a 0.5' error, I would be perfectly happy (currently I am usually around 1. 0' to 2.0'). Guess, I really need some more practising.

Wolfgang

Fred Hebard (Fred@ACF.ORG) schrieb:

Dear Wolfgang,

I was in a position similar to yours 5 months ago. My advice would be
to not worry too much yet about non-adjustable sextant errors until you
can get consistent readings with a standard error of less than 0.2' of
arc and to within 0.5 to 0.7' of your known position (Hc - Ho < 0.5').
(It the positions start coming in with 0.1 of your known position, then
you will know that your sextant is pretty accurate at that angle).
That might take more than one hundred observations of 3-6 sights each.
You could then start to determine whether there was any systematic
variation in (Hc - Ho) with Ho.

George Huxtable answered your question about the distance (angle)
between stars in a post in January,
http://www.i-DEADLINK-com/lists/navigation/0301/0029.html. I have not
implemented this method to a large degree, only a few tens of
observations. I've been concentrating instead on timed observations,
which are more relevant to practical navigation. The most difficult
part for me has been timing the sight accurately, which is critical for
accuracy.

Hope this helps,

Fred