NavList:

Alex it is interesting that a certificate would show a 10" error over the whole arc! I guess a simple IC of 10" would take care of that! What was your experience like having the sextant checked by Freiberger?

 

Ken thanks for your comments re: managing errors <1'. I haven't dug into this issue the way you suggest but have kept some data I have been collecting to get an idea of sextant/observation performance that I have listed below.

 

I kept this data as it took a few of the variables out like bouncing on the boat, odd horizon conditions etc. So, to me, the results represent the upper end of performance that I might expect with single shots. No question more statistics sheds more light on the issue. Good challenge trying to track down those <1' instrument errors.

 

- These are differences in minutes of angle between Hc and Ho, approximate position being GPS position

- Mostly star sights

- Taken at different times over the past year or so

- All taken with an artificial horizon

- All taken under ideal conditions i.e. calm clear

- No averaging or plotting

 

0.4
0.3
0.4
-0.4
-0.5
0.2
0.1
0.1
-0.1
0
-0.2
0.1
-0.4
0.2
-0.1
0.4
-0.3
0.3
0.1
0
-0.1
0.3
0.1
-0.1
-0.3
0.1
0.4
-0.2