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Frank wrote [5988]: You found deviations as large as 0.6 minutes or arc in
the clearing with a
standard deviation of 0.3 minutes. That's a lot! Though I certainly can't
guarantee it, I believe that my clearing results are accurate to 0.05
minutes of arc so I would say that you still have some things to fix. Even
in the year 1790, a discrepancy of 0.6 minutes of arc in clearing a lunar
would have been counted as "too large" except as a rough approximation.



The results from my test cases with my input data into Frank's prediction
model [5932] were as in columns 2-3 below. All data 1-8 are in minutes of
arc directly read out from Frank's model.



I still claim that my own LD prediction model is rather precise well aware
of that I use old-fashioned methods. My  results with the same input data,
except for Jeremy's first lunar - case 8, as per above in my own model give
errors in LD as per column 4. Column 5 is just a conversion to compare
figures in arc min with what I got from Frank's model. So the relevant
comparison is between column 2 and 5 :





      Case
     Frank's error in LD
     Frank's error in longitude
     My error in LD

      In arc sec
     My error in LD in arc min

      1
     0'
     1'
     -5,5"
     -0,092'

      2
     0,6'
     19'
     -2,1"
     -0,035'

      3
     -0,3'
     10,3'
     5,5"
     0,092'

      4
     0,3'
     9,6'
     -1,5"
     -0,025'

      5
     0,1'
     3,3'
     0,06"
     0,001'

      6
     -0,2'
     5,5'
     -2,3"
     -0,038'

      7
     0,4'
     11,1'
     -0,5"
     -0,008'

      8
     0,1'
     1,8'
     -
     -

      Mean
     0,125'
     7,7'
     -0,91"
     -0,015'

      Std. Dev.
     0,3'
     6,0'
     3,3"
     0,055'




Frank's comment that an error of 0,6' was to large in 1790 can be
questioned. I would say that navigators then were likely not unhappy to find
longitude within 15-20 M (0,5-0,7 min of arc in LD). The errors in my LD's
are referred to test cases taken from text books. You can of course always
ask what is correct.



Kent N

----- Original Message -----
From: 
To: 
Sent: Sunday, August 03, 2008 3:02 AM
Subject: [NavList 5988] Re: My first Lunar


>
> Kent, you wrote:
> "I have now made a comparison between Frank's model and mine and here are
> the results. In all cases I have used my own way to compensate for
> oblateness/flattening. By using my data in Frank's modell error in lunar
> and
> and error in longitude are read out.
> [...]
> So it seems to me that my model is rather good. The deviations are
> probably
> that I model e.g. refraction and oblateness/flatness in a different way
> from
> Frank."
>
> You found deviations as large as 0.6 minutes or arc in the clearing with a
> standard deviation of 0.3 minutes. That's a lot! Though I certainly can't
> guarantee it, I believe that my clearing results are accurate to 0.05
> minutes of arc so I would say that you still have some things to fix. Even
> in the year 1790, a discrepancy of 0.6 minutes of arc in clearing a lunar
> would have been counted as "too large" except as a rough approximation.
>
> -FER
>
> >
>



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