[time-nuts] Time transfer, internationally before GPS

Tom Van Baak tvb at LeapSecond.com
Mon Mar 3 23:04:24 EST 2014

> The piece didn't say anything about correcting for acceleration.

Hi Max,

True, but at one point the video mentioned microsecond resolution, and at that level, no relativistic corrections for airplane trips are needed.

If you want to get down to nanoseconds, then yes, you will want to apply altitude (gravitational), velocity, and Sagnac corrections.
You can use my rel.exe tool (www.leapsecond.com/tools/) to calculate the two relativistic effects:

C:\tvb> rel 35000ft 500mph 8hr
** Altitude 10668.000 m (35000.000 ft, 6.629 mi) 1.161e-012 blueshift
     4181.381949 ps/hour
      100.353167 ns/day
** Velocity 223.520 m/s (804.672 km/h, 500.000 mph) -2.779e-013 redshift
    -1000.607783 ps/hour
      -24.014587 ns/day
** Net effect (GR+SR) 8.835e-013 shift
     3180.774165 ps/hour
       76.338580 ns/day
** Duration 28800 seconds (8.000 hours, 0.333333 days)
    25446.193322 ps total
       25.446193 ns total
        0.025446 us total

So for an 8 hour flight at 500 mph at 35,000 feet the time dilation correction is only about 25 ns.
Add to that the Sagnac correction for East-West or West-East travel between USNO and NPL, about +/- 22 ns.


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