Celestia Forums

Recently discovered Celestia, great work!

Some idea (which might have come up before): It would be nice to have "local earth support". I mean to be able to setup earth-latitude/longitude/elevation above sea level, and use it like a regular astronomy tool. I tried this, but found discrepancies between predicted and real planetary positions.

Navigation in earth-coordinates would also be a nice feature, as I didn't find a way to keep the horizon always nicely in horizontal position.

Best wishes,

Marc.-

Gortu wrote::arrow: Recently discovered Celestia, great work!

Some idea (which might have come up before): It would be nice to have "local earth support". I mean to be able to setup earth-latitude/longitude/elevation above sea level, and use it like a regular astronomy tool. I tried this, but found discrepancies between predicted and real planetary positions.

Navigation in earth-coordinates would also be a nice feature, as I didn't find a way to keep the horizon always nicely in horizontal position.

Best wishes,

Marc.-

Celestia offers already a number of features in this direction. More are on my coding list since quite a while.

I can only tell you off-hand what the Celestia-KDE Linux version has.

1) Menue: GoTo LongLat
So enter your preferred longitude/latitude for earthbound observation you can go there immediately.

2) The key '*'=lookback is often useful when landing 'face-down';-).

3) ALT+S => Goto Surface (in Windows it should be CTRL +S instead)

4) ALT+F => Altitude-Azimuth mode (CTRL +F in Windows). In this mode the Left-Right, Up-Down keys control Azimuth and Altitude, respectively, just as you wanted to have it.

Very soon, we shall incorporate a data base of about 500 locations on earth (cities, observatories...) and on other celestial objects (landing sites etc)

Moreover cursor read out is planned for various coordinate systems.

I do not understand that you found discrepancies with planetary positions. Celestia is /most/ accurate and I and many others usually get the correct results.

Bye Fridger

By default "Y" sets Sync Orbit mode which means that you'll be stationary with respect to the rotation of the body you've selected.

BTW, Fridger, CTRL+G is goto surface mode in Windows... (not CTRL+S)

jrobert wrote:By default ALT+S sets Sync Orbit mode which means that you'll be stationary with respect to the rotation of the body you've selected.

BTW, Fridger, CTRL+G is goto surface mode in Windows... (not CTRL+S) :wink:

Good you put this right. I just checked the code as well.

In Celestia-KDE some of these key combinations are already occupied with standard functions, hence the alternate default assignments. Of course all keys may be reassigned in Celestia-KDE.

I rarely use the Windows version (no reason why I should;-))

Bye Fridger

Fridger, glad to see you back!!

Aaaargh! Months using Celestia as an earth-based planetarium, rolling and pitching to get horizontal position, and Alt-Azimuth mode had been there all the time!!

I haven't found that mode in the documentation, nor the "Goto Surface" feature.

Respecting discrepancies in planetary positions, I've found these too, when observing jovian moons through my small telescope. Starry Night, for instance, computes positions far more accurately. I've tried playing with light-travel delay in Celestia, but it doesn't improve things significantly. However, I'll try again when Jupiter re-appear in good conditions.

Pollux wrote:Aaaargh! Months using Celestia as an earth-based planetarium, rolling and pitching to get horizontal position, and Alt-Azimuth mode had been there all the time!!

I haven't found that mode in the documentation, nor the "Goto Surface" feature.

These features are still in development . . . Alt-azimuth mode needs some work--if you adjust altitude and azimuth simultaneously, the horizon leveling doesn't work.

Respecting discrepancies in planetary positions, I've found these too, when observing jovian moons through my small telescope. Starry Night, for instance, computes positions far more accurately. I've tried playing with light-travel delay in Celestia, but it doesn't improve things significantly. However, I'll try again when Jupiter re-appear in good conditions.

I very much doubt that Starry Night is more accurate . . . I've verified that the positions of the Galilean satellites are correct by comparing them with data from JPL's Horizons ephemeris system. Were you perhaps using a pre-1.3.0 version of Celestia before?

--Chris

Pollux wrote:Aaaargh! Months using Celestia as an earth-based planetarium, rolling and pitching to get horizontal position, and Alt-Azimuth mode had been there all the time!!

I haven't found that mode in the documentation, nor the "Goto Surface" feature.

Respecting discrepancies in planetary positions, I've found these too, when observing jovian moons through my small telescope. Starry Night, for instance, computes positions far more accurately. I've tried playing with light-travel delay in Celestia, but it doesn't improve things significantly. However, I'll try again when Jupiter re-appear in good conditions.

Sorry, you must have made something wrong or have used an old version! I have personally checked many many delicate mutual events among the jovian moons and always found them within a few seconds correct, relative to J.Maeus' official data that you may also find in various volumes of Sky & Telescope. I have also timed such events through my own, fairly big telescope....If I would not have switched the light time delay on (LT) in Celestia, that I have coded myself, then all those timings would have been incorrect by at least 19 minutes! So I do not at all understand what you are talking about in your post....

Bye Fridger

I'm sure both of you are right. I didn't know that Celestia achieved that degree of precision, and was talking about observations some months ago. Celestia version used was 1.3.0, so maybe (sure) I'm doing something wrong, as a novice astronomer I am.

I'm sorry about posting without checking the info first. As I said before, I'll try again when possible. I'll tell you then.

By the way, how do you simulate what you would see through a telescope, given its parameters, as it's viewed in post "Telescope question again"?

Well, I've checked galilean moons' positions taken from an astronomy magazine both against Celestia and Starry Night, and they're STUNNINGLY ACCURATE on both programs!

Other Jupiter's moons differ noticeably, but at the moment, I've got no reference data to check positions. I'll search for it.

I was making some mistakes on both programs:
- Applying LT delay in Celestia without selecting Jupiter first.
- Enabling daylight savings (in Starry Night) when not applicable here in Spain (february).