I made a post about the potential of a negative leapsecond a week ago -- https://news.ycombinator.com/item?id=32125171 https://news.ycombinator.com/item?id=3212

I made a post about the potential of a negative leapsecond a week ago -- https://news.ycombinator.com/item?id=32125171 https://news.ycombinator.com/item?id=32125171 I was partially motivated to write about leapseconds because I'd spent much of the day trying to construct leapsecond tests for my telescope pointing code. You're absolutely right, leapseconds don't help astronomers. Casual astronomy will do a one star alignment, so in effect they'll point at a star find out where it is and from it effectively compute the UT1 UTC offset (along with correcting other sources of pointing error). This applies no equally for electronic or manual pointing. More serious astronomy with use the IERS Bulletin A data. https://datacenter.iers.org/productMetadata.php?id=6 https://datacenter.iers.org/productMetadata.php?id=6 Without it you UTC would only get you within 0.9 seconds (and you won't know the other polar motion terms), so you might as well just platesolve. If you do have the IERS data you have to then back out leap seconds. You note you need constantly updated tables to do that, but it's worse than that: All over the place systems are getting their UTC replaced with leap-smeared UTC without the operators knowledge. You can't just back out leapsmear especially if you don't know you have it. I'm sure leapseconds sounded like a good idea on paper and when only a small number of especially exotic systems needed to deal with them. But the pervasive computerization since the 1960s has increased the cost of leapseconds by many orders of magnitude. > But eventually it will build up enough error that it eventually has to be addressed Yes, in 4000 years or so people can adopt new timezones that are shifted over by an hour. We already have comprehensive support for timezones, and support for them changing (as they're fairly vulnerable to political whim), computers handle them reasonable well-- and importantly they're primarily a presentation element so they don't mess up precise timekeeping. Maybe in 4000 years no one will even care-- perhaps everyone will have finally switched to SWATCH INTERNET TIME. But regardless, a timezone addition/change every few thousand years is a much better situation than we have with leapseconds.