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I wrote:
>>For 18 June 2013 at 3:30:00UT1, geocentric lunar distance to Altair:
>
> USNO MICA 2.0
> 106 34 28.48 (= 106 34.4747), calculated from geocentric apparent places
> with respect to true equator and equinox at TT = 03:31:07.1.
>
> 12 49  1.478  -8 12 48.78  Moon
> 19 51 28.291  +8 54 23.41  Altair

I should have explained that a flaw in MICA 2.0 makes it impossible to
realize the full accuracy of the program if one uses UT1 to compute Moon
coordinates. At 03:30 UT1 MICA says:

12 49  1.557  -8 12 49.17

With that position the separation angle from Altair is 106 34 27.36 (=
106 34.4561), 1.1″ less than from the value quoted above. The reason is
that MICA thinks delta T is 69.289, but it's really 67.118. There is no
provision for manual input. Thus for best accuracy one must convert
03:30:00 UT1 to 03:31:07.1 TT and select the TT scale in MICA.

I think MICA 2.0 uses the JPL DE405 ephemeris. I don't have a DE405 file
on hand, but DE406 is the same integration in a more compact storage
format. In this case there's practically no difference between DE406 and
the recent DE422 ephemeris. RA is .001 s different, declination
identical at 0.01″ precision.

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