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Why Is There a Lag In The Position Of Jupiter's Moon's And GRS? (Answer: SS7 Settings > Precession > Light Time)

Dan Durkin

February 05, 2022 23:35

Answered

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I am using Sky Safari7 Pro. For me, the display for Jupiter and its moons appears to lag the actual time by about 50 minutes. For example, tonight’s (Feb 5) Io Shadow transit ending, which is scheduled correctly to occur at 6:18, is animated to occur at 5:29.

I checked my older Sky Safari 6 Plus and there, the display is correct.

I check all my time and location settings, and they appear correct.

The time lag of 50 minutes is close to the time light would need to travel from Jupiter to the Earth. Do I have a setting incorrect.

Thank you for your help.

 

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8 comments

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  bruce lamoreaux February 05, 2022 23:45

  I check from SS7 and SS6 plus at my location the Io shadow ends at 19:18 on both.

  bruce

   

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  Dan Durkin February 05, 2022 23:50

  Bruce - you checked the listed time or checked the animation (display) of Jupiter and the transit, or both?

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  bruce lamoreaux February 05, 2022 23:54

  Selected info on Jupiter and checked the Io shadow start and finish time.  Touched the clock to see where Io shadow is on Jupiter. 
  bruce

   

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  Dan Durkin February 05, 2022 23:55

  Perhaps I should add, "6:18 PST".

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  bruce lamoreaux February 06, 2022 00:04

  I just checked anther prediction at Sky and Telescope and it’s within 8 minutes so location will be important. 
  bruce

   

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  Dan Durkin February 06, 2022 00:06

  Okay, well my event time is listed correctly but the Jupiter display is off. It would be helpful if someone would tell me what magic button to touch to make it proper.

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  Dan Durkin February 06, 2022 00:15

  I just checked Saturn and its moons on SS7 Pro and SS6 Plus. The display on SST Pro lags by 90 min, which corresponds to the light transit time to earth. Somehow, events are displaying by local "planet" time. SS6 Plus is correct.

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  Dan Durkin February 06, 2022 00:26

  Okay - mystery "solved". The magic box is under Settings: Precession: Light Time. My Light Time was off. I sure hope that's not the default upon installation, and am nearly certain I've never gone into this setting before.