Here's a recent publication from JPL on UT1-UTC earth observation parameter
extraction:
Nikki A. Zivkov, Durgadas S. Bagri, Konstantin V. Belov, Christopher S. Jacobs,
Gabor E. Lanyi, Charles J. Naudet, and Alexander S. Tolstov. Extracting the
UT1-UTC Earth Orientation Parameter from VLBA Multi
You raise an interesting question about using the Earth Orientation Data. The
precision orbit determination folks at JPL probably use the EO data from some
other source when doing their thing, since it’s all post processing anyway
mostly from code and carrier phase observables, not decoding the
I’d venture that nothing *on the satellite* is aware of UT1. That would be
done in the ground segment. The satellite itself probably does not know where
it is, it just plays the specified messages generated from the model based on
the internal clock. On the ground, they measure the observabl
Most spacecraft don’t know any sort of time in an absolute time scale. They
have a free running counter at some rate, and everything is done in terms of
SCLK. (Spacecraft Clock). Someone on the ground does a process called “time
correlation” to relate local clock on spacecraft to some other sy
Let’s back of the envelope the impact of a 1 second error in a longitude sight.
The Sun moves 360 degrees in 86400 seconds. A one second error is then about
0.004 degree. But in equatorial km, let’s assume 40,000 km circumference, so
40,000 km in 86,400 seconds (yeah, it’s actually less, siderea
