>> Anybody studied the influence of the Sun's gravity on clocks in GNSS satellites? Steve Allen said: > This particular effect is small, and I am not sure that the GPS clocks are > stable enough to reveal it. I was at an astronomy talk last night. One of the interesting comments by the speaker is that the JWST is wonderfully stable. It is constantly cold as compared to the Hubble that goes into the Earth's shadow every hour with the associated thermal swing. I assume the guys in the GPS control room have lots of stability data. Are there times when a satellite will stay in the sun for several orbits? Any published data? Picking an orbit to maximize the sun's gravity delta will go into the shade. -- These are my opinions. I hate spam.

On 1/31/23 10:38 PM, Hal Murray via time-nuts wrote: >>> Anybody studied the influence of the Sun's gravity on clocks in GNSS > satellites? > > Steve Allen said: >> This particular effect is small, and I am not sure that the GPS clocks are >> stable enough to reveal it. > I was at an astronomy talk last night. One of the interesting comments by the > speaker is that the JWST is wonderfully stable. It is constantly cold as > compared to the Hubble that goes into the Earth's shadow every hour with the > associated thermal swing. > > I assume the guys in the GPS control room have lots of stability data. Are > there times when a satellite will stay in the sun for several orbits? Any > published data? Here: https://gssc.esa.int/navipedia/index.php/Satellite_Eclipses they say every satellite has 2 eclipse seasons/year lasting 7 weeks. And interestingly, the satellites lose attitude control during that time, and shouldn't be used during that time.  I guess I never thought about this, I would have thought they were 3 axis stabilized with a star tracker or similar, so they could Nadir point all the time. > > Picking an orbit to maximize the sun's gravity delta will go into the shade. > >