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    Re: Choice of timepiece
    From: Frank Reed
    Date: 2009 Nov 13, 20:34 -0800

    Lu, you wrote:
    "but I'm looking at heavens-above.com and its display is about seven seconds 
    slower than time.gov.  I suspect that while, as they claim, they have very 
    accurate time-keeping on their server, they're not compensating for 
    propagation delay across the Internet."
    Interesting! Seven seconds is a big error. I just experimented with three 
    different browsers (Internet Explorer, Google Chrome, and Firefox, all 
    running under Windows Vista). I was able get de-synchronizations of the 
    various time displays of up to half a second by minimizing and then restoring 
    the browser windows (which is to be expected since the animated time display 
    is just a javascript function), but when I refreshed the page, they were all 
    back within an indistinguishable fraction of a second compared to WWV. And I 
    think we *have* to believe that they are compensating for Internet 
    propagation delay when the page first loads. I don't have any special 
    pipeline to that web site!
    I just spent five minutes away from my computer and have come back to see how 
    they're doing. The javascript displays in the three browsers have de-synched 
    by about a quarter of a second.
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