On 12/28/2011 12:17 AM, unruh wrote: > On 2011-12-28, 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. > > No they do not. They use GPS. As has been discussed here gps can be made > accurate to a few ns. GPS is used by radio astronomers to synchronize > very long baseline arrays. > (Yes, I also thought that gps was not accurate enough. I was wrong)
As a fellow astrophysicist you know that you don't just use GPS for this like you would finding your way around the streets of Vancouver. This is way beyond those kind of calculations. Of course in astrophysics even 1 km is below the noise level... Danny _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
