celestial nav thought experiment

[cthomas]

Last month, close to the full moon, I watched as the moon transited Jupiter. It got me to thinking. Is it safe to assume that when these two bodies are at their closest, their GHA's the same? Could one take sighting and determine a local time such that the two bodies are closest then compare to almanac to determine GMT? I have tried to find the lunar reduction tables but they seem to have disappeared off of the web.