Sun position in Sky view

[srcejon]

Hi,

It looks as though the position of the Sun in the Sky view may be slightly off due to J2000/Jnow difference.

Here's what I see in the Web client (which is the same as the Windows client):

RA: Is given as 20h43m...

If I look at NASA JPL Horizons for this time, I get:

RA: Is 20h42m... (Uses ICRF which I believe should be very similar to J2000)

If I enter that RA in the Search in WWT with J2000 set, it doesn't point to the Sun (as in the pic above).

In Stellarium:

It shows J2000 as 20h42m... but Jnow as 2043m...

If I enter the Jnow RA from Stellarium in the Search in WWT, then it points at the Sun.

So it looks like WWT might be using Jnow rather than J2000 for the position of the Sun somehow.

[srcejon]

Likewise for the Moon and Jupiter.

[patudom]

@srcejon, thank you for looking into this and raising the issue. I don't think it will be an easy fix to convert all the Solar System coordinates to J2000, but at the very least, WWT's labeling should be clearer on what it is using. We will see about adding better labels in the short term to the web client (or at least in the WWT documentation) and try for a better solution in the longer term.