NavList:

Frank wrote

You did a "time sight". That old expression "long by chron" was common in logbooks in the 19th century in some traditions, but the distinction being made had little to do with the mathematical analysis you've written up. Also there is some lingering confusion about these sights arising from 20th century "backfilling".

I could have written:

I did a time site.

I determined my long using app xyz on my phone.

I repeated the calculation with a different latitude. My long was the same.

How boring that would have been! It probably would not have resulted in the extremely interesting Shackleton/ Royal Navy practice thread.  Maybe I should have mentioned that whereas Sumner's position line took him to Smalls Light mine took me to the South Pole.