Celestial nav requires expensive equipment and intensive
training; and in any case is virtually impossible to carry out while
flying a private aircraft.

The equipment isn't really that expensive. You can buy a reconditioned
aviation sextant for $990

That's what I call expensive!

and some books of astronomical tables (or, more likely these days, a
program for your calculator or laptop).

Because of the small market for those books, I assumed they are pretty
darned expensive, too. But I found a Nautical Almanac at Amazon for
under $20. Not sure if it's the same book, but it seems to be. When
I tried to find a copy of Star Tables, all I could get was stuff about
Star Trek.

There is certainly an investment in training (probably 20 hours of
classroom time).

Well, I didn't count them, but I'm sure I spent a hell of a lot more
than 20 hours learning celestial nav as an aviation cadet at Pensacola
and Corpus Christi. The University of Illinois must have thought so,
too; when I got out and went back there, and showed them my service
records, they gave me 30 semester of college credits in celestial
navigation! That's a full college year of work! (That enabled me to
get my degree and begin grad work one year earlier than I expected.)

Celestial nav is cool, but just isn't useful any more. It's an interesting
thing to learn, but only any practical value is long since gone.
GPS drove the last nail in the celestial coffin 10 years ago.

About five years ago, a friend and several of his friends who have
much more money than I have, sailed a catamaran around the world. A
big one, both hulls 40 feet long. He carried three GPS units, but he
also learned celestial nav before he set out, just in case.

vince norris