NavList:

Brad,

In further reference to your post [NavList 12605], and with the same assumptions as the ones detailed in [NavList 12606], I completed my "examples list" with a default value of 12 FT for the Observer's eye this time, and I am getting the following results :

Lunar Distance Observation Time UT = 15h47m58s1, and
Observed position : S 20°49'29" / E 227°39'51"

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Indeed this position is both :

quite close from your "starting" position, (S 20° 49' / 227° 40'30"), and also

quite close from the one which is published (S 20°49' / E 227°40'30")

*******

The only difference between our results here regards the times : your value is 15h48m17s, with a 19 second difference from the value I derived.

19 seconds of time is only just over 0.1' in Distance between Limbs and this might be quite simply explained by a possible difference in the Refraction algoritms used (the Sun is only 6° over the horizon, and I am not sure that refraction is consistently known to 0.1' accuracy then). However, our longitudes agree to better than 3 seconds of time ... quite strange here !

Maybe a difference in Apparent places computations ?

For Aug 04, 1773 at TT = 15h48m00s0, DE406 yields :

SUN RA = 08h59m34s08, Dec = N+17°05'41"8 , and MOON RA = 22h31m53s45 , Dec = S-06°52'10"9 , Par = 56'914 , while I am deriving the following values :

SUN RA = 08h59m34s07, Dec = N+17°05'41"8 , and MOON RA = 22h31m53s35 , DEC = S-06°52'10"3 , Par = 56'913.

Evidently, this minute difference (less than 2") in the Apparent Coordinates cannot explain these some 16 seconds still unaccounted for, unless ... your time value is in TT and not UT ? (I did my computations with ... deltaT = 16.4s !).

Any clue here, Frank ?

Best Regards

Kermit

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