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    Re: Choice of timepiece
    From: Lu Abel
    Date: 2009 Nov 13, 20:56 -0800

    Interesting.   I went back to heavens-above.com and it displayed time 
    dead on as compared to my WWVB clock.   I then brought up time.gov and 
    suddenly heavens-above was about five seconds slow!!   I wondered if 
    there might have been problems with the Javascript engine, resource 
    sharing or whatever that caused it to slow.   I played a bit with 
    bringing up time.gov again and again to see if I could make 
    heavens-above slow down and suddenly it was back in sync!    Since then 
    I've played with both time sources, bringing up new browsers and 
    different ones and I haven't been able to shake heavens-above.  
    Ah, the joy of computers!
    frankreed@HistoricalAtlas.com wrote:
    > 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.
    > -FER
    > >
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