NavList:

Dear Paul (Hirose),

I geeked out and summarized, hopefully correctly, your original and compact Ageton Monte Carlo test results in a spreadsheet (omitting those for a tabulation interval of 2'). If I have understood right, the main conclusions are:

·      Increasing the tabulation interval (e.g. from 1' to 0.5') improves accuracy,

·      Increasing the danger zone limits (e.g. from K<±5º to K<±8º of 90º) increases the calculation workload with no significant improvement in accuracy,

·      Optimum use of Sadler is for a danger zone of K<±2-3º of 90º,

·      Increasing the tabulated values with decimals from <6º to <36º  improves accuracy,

·      t (LHA) is a good criterion of the danger zone (instead of K that has to be calculated) only for the use of interpolation but not for the use of Sadler,

·      Rejecting sights in the danger zone significantly improves accuracy,

·      Restricting Dec to <75º (in which case all navigational stars are included) improves accuracy,

·      The worst azimuth errors occur at high Hc.

For the original Ageton the statistics you have provided are comprehensive. I would like to ask, however, provided you have the time and interest, some statistics for the following cases of the Bayless/Ageton table:

A.    Use of Sadler for K<±3º

1.     Dec<90º/decimals for <37º 25'

2.     Dec<90º/no use of decimals at all

3.     Dec<75º/decimals for <37º 25'

4.     Dec<75º/no use of decimals at all

B.    Use of Sadler for K<±2º:

1.     Dec<90º/decimals for <37º 25'

2.     Dec<90º/no use of decimals at all

3.     Dec<75º/decimals for <37º 25'

4.     Dec<75º/no use of decimals at all

“decimals for <37º 25'” refers to a potential modification of the Bayless/Ageton table, in which the decimal values would be extended beyond 5º, up to the angle where B changes from 9999 to 10000.

Also, do you have any indication how would the accuracy be affected if Ho was extended below 5º, say down to -1º?

Cheers,

Michalis Vaidanis

38ºN 024ºE