Re: [time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?
Of course... I am designing a GPS receiver as my day job and didn't think of that ;) Henry On Mon, Mar 1, 2010 at 8:36 PM, Mark Sims wrote: > > Pretty trivial to do with GPS where a 1 ns error is under 1 foot of position > error (and a geodetic grade GPS can give sub-millimeter accuracy)... even a > cheap consumer grade unit is under 10 feet of error. 1.26 us of orbital > change is over 1100 feet of error. > > One trick is to compare the pre-earthquake GPS almanac/ephemeris data with > the post earthquake data. I suspect that a lot of geodetic monitoring > stations are scrambling to keep up with what the earth is currently doing. > > > --- > How would one go about verifying this? The angular difference after 1 > year is about 3E-8 radians, which is probably well beyond the absolute > pointing accuracy of any telescope, and swamped by lunar tidal > deceleration anyway. > > > _ > Hotmail: Free, trusted and rich email service. > http://clk.atdmt.com/GBL/go/201469228/direct/01/ > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Henry Hallam Sent from my Laptop ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?
3E-8 radians is 0.03 microradians. A microradian is about 5 arc-seconds, so about 0.15 arc-seconds per year. I think that's in the range that could be observed either optically or by VLBI. -John = > How would one go about verifying this? The angular difference after 1 > year is about 3E-8 radians, which is probably well beyond the absolute > pointing accuracy of any telescope, and swamped by lunar tidal > deceleration anyway. > > Henry > > On Mon, Mar 1, 2010 at 7:36 PM, mc0fred wrote: >> Interesting that the effect could be this large. >> >> http://www.smh.com.au/technology/sci-tech/chilean-quake-shifted-earths-axis-nasa-scientist-20100302-peqe.html?autostart=1 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?
How would one go about verifying this? The angular difference after 1 year is about 3E-8 radians, which is probably well beyond the absolute pointing accuracy of any telescope, and swamped by lunar tidal deceleration anyway. Henry On Mon, Mar 1, 2010 at 7:36 PM, mc0fred wrote: > Interesting that the effect could be this large. > > http://www.smh.com.au/technology/sci-tech/chilean-quake-shifted-earths-axis-nasa-scientist-20100302-peqe.html?autostart=1 > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Henry Hallam Sent from my Laptop ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
