Re: timestamp resolution

[Hans Aberg]

I made a post to the moderated Usenet newsgroup sci.astro.research,  
"Julian day numbers and leap seconds", and there are so many  
responses, I cannot summarize them here.

The question of finding a good time suitable for distributed  
computing as well as in astronomy and sciences, plus syncing it with  
legal time is very complicated, and probably requires a committee of  
scientists and experts from a number of fields.

But one suggestion might using say TAI (International Atomic Time,  
with letters in French grammatical order), or possibly GPS time. It  
might be synced with say JD counted in seconds so that the difference  
becomes 0 today. Then leap seconds can be then be viewed as a feature  
of the UTC legal time.

TAI is the mean of highly accurate Cesium atomic clocks (the SI  
second is defined in terms of Cesium transitions), accuracy better  
than 10^-7, and is broadcast, so it can be used in computers via  
radio-controlled clocks (which are now commonly sold). see <http:// 
en.wikipedia.org/wiki/International_Atomic_Time>.

As for POSIX, I know that in some quarters, for example NASA when  
there is a satellite launch, one is very concerned over the problem  
not knowing which time the computers are set to. So it might be good  
to fix this gap in the POSIX standard.

  Hans Aberg