Danny Mayer <[email protected]> wrote: > On 12/27/2011 8:48 PM, [email protected] wrote: >> Danny Mayer <[email protected]> wrote: >>> On 12/24/2011 8:10 PM, [email protected] wrote: >>>> John Hasler <[email protected]> wrote: >>>>>> The open sky nearest the OPERA detector is straight up through 1400m of >>>>>> rock. >>>>> >>>>> Jim Pennino writes: >>>>>> And the easiest open sky to get to is horizontally down the tunnel to >>>>>> the entrance which is next to a freeway. >>>>> >>>>> Yes, the entrance is next to a freeway. The entrance to the LNGS >>>>> facility where the OPERA detector is located is near the middle of the >>>>> 10 km long Gran Sasso highway tunnel. >>>> >>>> The bottom line is that the only thing that is relevant is how easy it is >>>> to get to a GPS antenna with an open view of the sky. >>>> >>>> Everything else is bloviation. >>> >>> GPS is not used for this kind of thing, they are too inaccurate, so it >>> doesn't matter. They use atomic clocks. >>> >>> Danny >> >> How do you measure distance with an atomic clock? >> >> > > That's a complex question. GPS (even the military version) is not > accurate enough. > > Danny
No, it is not complex; you can't measure distance with an atomic clock. An atomic clock is used to measure time intervals. As for GPS, it is pretty trivial these days to determine an absolute location to parts of a centimeter for a fixed location. -- Jim Pennino Remove .spam.sux to reply. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
