Sky Safari timing is off

[MortonH]

Yesterday SS (Android basic version) predicted that the GRS would be central around 8:30pm and that Callisto would begin a transit around the same time.

When I actually observed it last night I noticed that Callisto didn't begin to pass in front of Jupiter until at least 30 minutes after SS showed the event starting.

I checked my location and time settings and even swapped between using the GPS setting and manually selecting Sydney - no change.

Is this normal or do we expect SS to be more accurate with its timings?

I didn't think to compare it with my Mac version.

[mithrandir (Andrew)]

Originally Posted by MortonH

Yesterday SS (Android basic version) predicted that the GRS would be central around 8:30pm and that Callisto would begin a transit around the same time.

When I actually observed it last night I noticed that Callisto didn't begin to pass in front of Jupiter until at least 30 minutes after SS showed the event starting.

I checked my location and time settings and even swapped between using the GPS setting and manually selecting Sydney - no change.

Is this normal or do we expect SS to be more accurate with its timings?

I didn't think to compare it with my Mac version.

SS is possibly showing the event time as it would be seen at Jupiter without taking the time it takes for the light to get back to Earth.

Finding that Jupiter moon transits were being seen at varying times was how Ole Romer's measurements lead to the first scientifically determined estimate of the speed of light.

You could ask the question on Y!.

Note: I know Romer's name is spelled with a o with a / through it, but non ACSII characters stuff up my Firefox.

[Steffen]

Originally Posted by MortonH

I didn't think to compare it with my Mac version.

On my Mac SS 1.8 shows that the Callisto transit started about 20:50 last night, and that the GRS transit time was about 21:13. The iPhone version of SS (4.0.1) agrees.

Cheers
Steffen.

[chappo (John)]

Change the 'Light Time' setting in 'Settings - Precession'.
The help file explains all ...

[MortonH]

This appears to be another limitation of the basic version. Roll on the Android upgrade!

[Steffen]

Originally Posted by chappo

Change the 'Light Time' setting in 'Settings - Precession'.
The help file explains all ...

Good find. Light time was turned on on all of my devices by default, as it probably should be. Maybe the Android default is different?

Cheers
Steffen.

[noeyedeer (Matt)]

mine had dynamic time as default on android... switched it to light time.

thanks (not that I use it much)

matt

[Steffen]

The dynamic time and light time settings are independent from each other, you probably want both on.

Cheers
Steffen.

[noeyedeer (Matt)]

ahh thanks Steffen.. I guess dynamic time means it's continuously updating the screen instead of needing a refresh. I will turn it back on anyways

thanks
matt

[Steffen]

Originally Posted by noeyedeer

I guess dynamic time means it's continuously updating the screen instead of needing a refresh.

No, it doesn't

The built-in help has a detailed explanation of all those settings.

Cheers
Steffen.