[duetosymmetry]

I believe every radio telescope has their own reference clock that lives at the site. The EHT team is not responsible for schlepping these clocks around. There are other reasons besides VLBI to have really good timing at the site—for example, pulsar timing.

[killjoywashere]

I think there was a question about that: they had some issues with two different standards and decided it was better to pick one type and use that at all locations even if they had to bring it up themselves.