[tor-relays] Question about authority clock skew

Hello everyone, how are you?

I was browsing the "Consensus health" page and something let me curious... What is the importance of the clock skew in the authorities with the resolution of microseconds?

Picture: 2020/04/13 - 13:37 UTC

Also, how the authorities compare their clocks? Using ntp daemon for example? I'm asking this here because I work in a time and frequency reference lab and have two NTP (stratum 1, connected directly to UTC(LRTE) timescale. And a stratum 2 that is discilplinned with the stratum 1 timeserver). So considering the microssencond accuracy did the keepers of these authorities care about the time source? Or any time source is ok?

Best regards and keep safe!

Luiz