[time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?
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 mc0f...@gmail.com 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.
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 mc0f...@gmail.com 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.
[time-nuts] Chilean quake shifted Earth's axis. The length of the day shorter by 1.26 microseconds ?
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.
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 hol...@hotmail.com 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.
