NavList:

Dear Lars,

Well done this time ! Yes, I immediately picked up the unusual way the altitudes were first tackled, and I was keeping confident it would not escape your attention for any long extra-time either.

But now, you are spot on !

Solving these Lunars through own Software yields:

15 Dec 2025 (with TT-UT +69.2 s),

GMT 06h31m33s with Cleared distance 33°21.9' and Position N46°37' W002°28' .

Your updated result at 06h31m49s is already good and greatly improved.

16 Dec 2025 (with TT-UT +69.2s),

GMT 06h34m54s with Cleared distance at 23°09.1' and Position N46°41' W002°30' .

Your updated result at 06h34m54s is spot on ! 

What is interesting is that Actual GMT times (or UT1 times since I actually computed the Ephemeris in such UT1 scale) and Actual position were:

15 Dec 2025

Actual UT1 06h31m27s with Cleared Distance at 33°22.0' and Actual Position N46°41.2' W02°19.9', from which I should have observed a Sextant distance corrected for Instrument Error of 32°33.18' vs. 32°33.0' recorded.

16 Dec 2025

Actual UT1 06h34m12s with Cleared Distance at 23°09.4' and unchanged Actual Position N41°46.2' W002°19.9', from which I should have observed a Sextant Distance corrected for Instrument Error of 22°23.57' vs. 22°23.3' recorded.

Lessons learnt:

(1) - In both cases I measured sextant distances slightly too short by about 0.2' on Dec 15th, then 0.3' on Dec 16th , most probably because I did not want to "loose" faint Mercury "over or inside" the brighter Moon Limb as I wanted to keep Mercury always visible. On December 16th observing Mercury was quite difficult.

(2) - In spite of their unfavorable environment - especially the second morning with so close Moon & Mercury Azimuths, not to mention the very low Mercury altitudes - the observations themselves indicate computed positions within 5' for Latitude and 10' for Longitude with obviously big error ellipses due to rather poor GDOP's .

Hopefully no typos here-above.

Best Regards and thanks again to you Lars, (night time here and almost no possibility to post on NavList from now on until end of next week)

Meanwhile ..., any other taker[s] (maybe with Paul Hiroses' "Lunar 4" ?) ?

Kermit