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SkySafari 5 Pro | Why Is The Position Of Jupiter's Moon IO Inaccurate? (Answer: Make Sure You Have Light Time Enabled In The "Precession" Settings)

Hello, I just find that the IO (Jupiter's satellite) position is inaccurate, just now when SkySafari 5 Pro in Android shows IO is in transit with Jupiter, while in my telescope I can see IO finished transit, looks like the program is about 10-20 late for the IO's position. I'm sure the time, date and location are correct and we don't use day light saving here in Hong Kong (GMT+8)

I double checked in Stellarium and IO position is correct there.


  • 0
    Bill Tschumy

    I'm sure our calculations are correct but you probably have some setting wrong.

    1. Make sure you have Light Time enabled in the "Precession" settings (this is the default).  If you have it off then we will show what it looks like if light is infinitely fast.  This will cause events to be reported around 40 minutes too soon.

    2. When you have the time set to NOW (or Realtime), does the chart's time match what you expect?  If not, we need to figure that out.

    3. Make sure your location is on Earth.  If you are orbiting some other object (say Mars) then all times will be from that location.

    There are probably a few other settings that could affect this.

  • 0
    Lawrence Mok

    Thanks very much, I did a factory reset then it seems to work fine now. It was like 10-20 minutes too late though, while location is correct. Will let you know if I notice anything again.

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