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Any chance getting you to share the code  I hve a TI-89 - believe they are
code compatible (basic)


> On 2018-01-15 8:18, Tony Oz wrote:
>> I programmed my TI-83 to do the computations as per Chapter 15 of
>> Henning Umland's excellent "Short Guide to Celestial Navigation", where
>> the author warns on the accuracy:[BEGIN QUOTE]
>> The maximum error of GHA and Dec is about ±0.6'. Results have been
>> cross-checked with Interactive Computer Ephemeris 0.51 (accurate to
>> approx. 0.1'). Between the years 1900 and 2049, the error was smaller
>> than ±0.3' in most cases (100 dates chosen at random). EoT was accurate
>> to approx. ±2s. In comparison, the maximum error of GHA and Dec
>> extracted from the Nautical Almanac is approx. ±0.25' (for the sun) when
>> using the interpolation tables. The error of SD is smaller than
>> ±0.1'.[END QUOTE]
>
> I coded his formulas in a program which compares them to the JPL DE431
> ephemeris at 1000 random times in the 21st century. It generally
> confirms Umland's accuracy claims. For Sun apparent place, semidiameter,
> and equation of time the program calculates an accuracy statistic for
> the whole set (square root of the mean squared error) and also remembers
> the single worst result.
>
> Apparent place error is the separation angle between a vector to the Sun
> calculated from the Umland formulas and a vector from the JPL ephemeris.
> It therefore combines the errors in RA and declination into a single
> number.
>
> .33′ apparent place RMS error
> .95′ max
>
> .006′ semidiameter RMS error
> .007′ max
>
> .90 s equation of time RMS error
> 2.95 s max
>
> :
> http://fer3.com/arc/m2.aspx/DIY-longterm-almanac-for-calculators-Hirose-jan-2018-g41198

   

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