Anyone know who was the originator of the matrix in the jpg file?
That looks like something out of Explanatory Supplement to the Astronomical Almanac, P. Kenneth Seidelmann -- I remember seeing similar-looking formulas in it long ago.
In any case, that looks like it'll only be good for a few centuries around our time.
Thanks. The book costs about $75, but it's possible that I might get an inter library loan from some university here in Calif.
I think the modern method is based on a 1976 paper by Lieske, et al. Expressions for Precession Quantities.
You'll likely find a copy at some well-stocked university library. I once found a copy at the UC Berkeley campus library. You can search the UC catalog online at WorldCat: University of California Libraries I did so, and indeed it was there. You may also be able to search other university libraries from your home.
Separate names with a comma.