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I would like to be able to read the time from an NTP server that is connected to a very accurate time source - an atomic clock, GPS clock, or similar. I can see an accurate clock here ( but would like an NTP version that I can use in some software that I'm writing.

Any help would be greatly appreciated.

EDIT: I've resolved the issue I was having (turns out it was my code, not the NTP server I was using)

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up vote 5 down vote accepted

Actually even if you find one NTP atomic based server(I dont think it exists) the NTP protocol isn't so accurate that your machine will have the same accuracy as the atomic clock. As wikipedia says:

NTP uses Marzullo's algorithm, and includes support for features such as leap seconds. NTPv4 can usually maintain time to within 10 milliseconds (1/100 s) over the public Internet, and can achieve accuracies of 200 microseconds (1/5000 s) or better in local area networks under ideal conditions.

An Atomic clock have a higher acurracy than NTP:

National standards agencies maintain an accuracy of 10−9 seconds per day (approximately 1 part in 1014), and a precision set by the radio transmitter pumping the maser.

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Sorry, I was labouring under the misapprehension that most NTP servers are only roughly accurate. It turns out that my code was actually at fault, rather than the NTP server that I was using. – endian Aug 23 '11 at 14:37

I believe those listed via are all sync'd with stratum 1 systems; I'd suggest starting with some reading at

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Note that the NIST maintains an official pool of NTP servers synchronized with their atomic-based time system: NIST Internet Time Service Pool.

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