The advance of the perihelion of Mercury is one of the four classical tests of general relativity. I wonder what's the most precise modern measurement of it. However, while scanning the literature, the most precise measurement seems to date back to a paper by Clemence in 1947:
The 50 papers that cite it are merely theoretical ones:
There is just one reinterpretation by Nobili and will in 1986,
but no new measurement. I know that there are other periastron shift data from the binary pulsar and others, but I'd be curious about the plantes of which Mercury shows the most pronounced effect. Messenger was a mission to Mercury in 2009, but I didn't find perihelion data from it. With all the precision telescopes built in the last decades, I cannot believe that or best data of this important test is 60 years old. Explanations of the technical difficulties of the measurement by an expert are also appreciated.