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Re: Lunars using Bennett
From: Peter Fogg
Date: 2008 Jul 4, 13:16 +1000
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From: Peter Fogg
Date: 2008 Jul 4, 13:16 +1000
On one issue George raises:
Interpolation.
In my 2003 edition of the tables, Bennett states clearly "do not attempt to
interpolate the tables", but then, he was not anticipating their use for
calculating lunars. In his paper on obtaining lunar distances, in the Spring
2003 issue of Navigator's Newsletter, he is a bit more ambiguous about
interpolation, saying about the tables in his book - "They are intended for
sight reduction without any interpolation (95% of errors of solution do not
exceed one minute of arc). However, if interpolayed, 95% of errors do not
exceed a few tenths of a minute of arc which may be acceptable." I expect
that Dave Walden has been careful to avoid any interpolation in his
automated procedure, but it would be useful to have that confirmed. If other
Bennett tables, computed with more decimal places, are to be tested in
future, presumably they will always require some interpolation.
In my 2003 edition of the tables, Bennett states clearly "do not attempt to
interpolate the tables", but then, he was not anticipating their use for
calculating lunars. In his paper on obtaining lunar distances, in the Spring
2003 issue of Navigator's Newsletter, he is a bit more ambiguous about
interpolation, saying about the tables in his book - "They are intended for
sight reduction without any interpolation (95% of errors of solution do not
exceed one minute of arc). However, if interpolayed, 95% of errors do not
exceed a few tenths of a minute of arc which may be acceptable." I expect
that Dave Walden has been careful to avoid any interpolation in his
automated procedure, but it would be useful to have that confirmed. If other
Bennett tables, computed with more decimal places, are to be tested in
future, presumably they will always require some interpolation.
Firstly; yes, for their original purpose interpolation was not recommended. However, the 6-figure tables, designed for lunar use, come with methodology for interpolation.
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