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Jim,

It might be helpful to add a column for Ho to these data, to see
whether there is any dependence for Hc-Ho.  This would suggest the
occurrence of arc errors such as are shown on sextant certificates.

Fred

On Feb 2, 2006, at 10:02 AM, Jim Hickey wrote:

> 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
>
>

   

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