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I've never understood the slavish devotion to catching the sun at the
exact highest point. If instead you work the noon sight as a normal LOP
sight using the normal tables (HO 214 etc.) you have a four minute
period when you work the sight with an LHA of zero and an AP within 30
NM of the DR and this method produces an LOP of the normally expected
accuracy.

gl

George Huxtable wrote:
> About the method Bligh would have used, to predict the time of local noon
> based on a morning Sun observation, Frank wrote-
>
> "I suspect this trick would be most useful in near-overcast conditions.
> Though you might not see the Sun enough times to convince yourself that it
> has reached its peak at noon, if you can look at a local time watch
> (corrected for the run of longitude from when it was set earlier in the
> day) then you don't need to see the Sun for more than the ten or fifteen
> seconds it takes to get a single altitude."
>
> =======================
>
> Well, it was even more useful than that. As long as the time of noon had
> been accurately predicted, then an observation of Sun altitude didn't need
> to be taken right at noon, or even very near to it. It could be taken up to
> an hour or more either side of noon, whenever a glimpse of the Sun appeared
> through the clouds.  And then, the latitude could be readily calculated
> from the altitude at that moment, knowing the time difference from noon,
> using the Ex-meridian Tables. That was primarily what those tables were
> for.
>
> George.
>
> contact George Huxtable, at  george@hux.me.uk
> or at +44 1865 820222 (from UK, 01865 820222)
> or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
>
>
>
>
>
>

   

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