I checked what the wiki says : beside "proofs of existence like satellite images" there are so-called "sources cited as official evidence...subject to OSM Community acceptance". The https://en.wikipedia.org/wiki/Earth_Impact_Database could probably serve as such "official evidence". According to this source, the "official" diameter would be 160km http://www.passc.net/EarthImpactDatabase/New%20website_05-2018/Vredefort.html. But I think it should (if at all) be tagged with something else than "crater", as not visible. There's also an "opposite" case here (not really a "crater", but the dome) https://www.openstreetmap.org/way/598692732/history. At least it's visible. There are currently those for the Vredefort which should be "consolidated" : "center" (not visible) https://www.openstreetmap.org/node/2086138326/history, "dome museum" (source not clear) https://www.openstreetmap.org/node/6631014785, this entry here (theoretical diameter) and I mapped the approximate remaining outline "on the ground" https://www.openstreetmap.org/way/1389346686. Should we probably "move" the discussion to https://wiki.openstreetmap.org/wiki/Talk:Tag:geological%3Dmeteor_crater ?