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That was my normal practice, too, Tom. Take the two brightest things in the 
twilight (other than an Airbus) with a decent bearing spread and get a 
handful of sights of each. Time is limited at dawn and dusk. Better to get 
three each of two than one each of three.

Hewitt


Sent from my iPad

On Mar 19, 2013, at 6:33 AM, "Tom Sult"  wrote:

> In real world CelNav One generally shoots the same star 3 to 5 times in  
succession followed by the second star 3 to 5 times in rapid succession. This 
increases the confidence in each site. One can graph these sites and throw 
out any outliers and even take a time average sites from the data.  I may 
have too much Neanderthals blood to understand statistics but...
> 
> Tom Sult
> Sent from my iPhone
> 
> On Mar 19, 2013, at 4:56, Jeremy C  wrote:
> 
>> 
>> Gary,
>> 
>> I would qualify this. Make sure that you have high confidence in those two 
lines you shoot. I can "feel" when a line is good when I shoot it. I hope 
that others do as well. I therefore weigh those LOP's much heavier than 
others. If you shoot 2 LOP's (be them celestial or terrestrial) and you muck 
one of them up, you can be way off.
>> 
>> I am one of those people who don't know statistics except in the broadest 
of terms. To compensate for this at sea, I remind myself that the celestial 
fix is approximate at best, and I know about what error of position I can 
expect based on the stars I manage to observe and the environmental 
conditions present at the time.
>> 
>> This same concept flows through my thinking on all fixes. Celestial being 
the least accurate, followed by visual bearings, then radar ranges, and 
finally GNSS which can be further subdivided by things such as WAAS, DGPS, or 
multi-system (L2) receivers.
>> 
>> While I applaud people's efforts to use statistics to boost fix confidence, 
I am well aware of the limits of precision and accuracy of the various means 
to determine position.
>> 
>> Jeremy
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