Celestia Forums

Hi to everybody,

and a great thank you for this great program i (what a shame) just discovered...

My first question:
I searched a lot in the forum in the last days, lots of talk about Celestia 1.6.0 and HDR, but if i browse the sourceforge rep. i cant find any version beyond 1.5.1...
Or am i stupid?

Where can i get the most recent version of Celestia for linux?

Thats for my NOOB question

A little information about my background...
I am a student of aeronautical engineering in stuttgart, shortly before my diploma thesis and specialized on space-system-engineering and space-applications. i am an (quite) experienced C++ programmer and currently work on a system-simulation open source program ( www.opensimkit.org / www.opensimkit.de )

kind regards,
Claas

p.s. if u all are very nice and kind to me and the things i think of MiGHT actually work... u might get an enthusiastic contributor very soon

aeronaut_23 wrote:I searched a lot in the forum in the last days, lots of talk about Celestia 1.6.0 and HDR, but if i browse the sourceforge rep. i cant find any version beyond 1.5.1...

See here:
viewtopic.php?f=4&t=11975

- rthorvald

HDR is not yet implemented officially... As pointed by Runar, the best for you is to get the source and build your own app. Welcome on board!

areonaut_23 wrote:Where can i get the most recent version of Celestia for linux?

1.6.0 hasn't had a pre-release yet. The code that will become 1.6 is being developed at sourceforge and the best way to get it is as stated above thru SVN. To acivate HDR, you need to pass the following statements to pre compiler statements.This will activate the HDR code in the executable.
Welcome aboard.
cartrite

thanks all for the kind and fast replies.
i followed the guide to install the development version it all worked flawlessly... thanks for the advice

i dont know if this i a bug or intended behavior, but when i dont disable "limit framerate" in the options tab, i get a framerate of apoximately 0.25/0.333...
after disabling this feature i now have approx. 1fps ( i know my machine is not suited at all for celestia ( pentium m, intel G915 graphics card ) )
also it occured to me that when running with composite windomanager emerald there is a lot of flickering in the output, but thats maybe not related to celestia...
anybody has some suggestions on that?

last of all a general question:

how precise is celestia concerning orbits of solar system bodies and there orientation?

just asking because i intend to read out the solarsystem bodies coordinates to use them in the system simulator i mentioned above.

greets claas

aeronaut_23 wrote:thanks all for the kind and fast replies.
i followed the guide to install the development version it all worked flawlessly... thanks for the advice

i dont know if this i a bug or intended behavior, but when i dont disable "limit framerate" in the options tab, i get a framerate of apoximately 0.25/0.333...
after disabling this feature i now have approx. 1fps ( i know my machine is not suited at all for celestia ( pentium m, intel G915 graphics card ) )
also it occured to me that when running with composite windomanager emerald there is a lot of flickering in the output, but thats maybe not related to celestia...
anybody has some suggestions on that?

last of all a general question:

how precise is celestia concerning orbits of solar system bodies and there orientation?

just asking because i intend to read out the solarsystem bodies coordinates to use them in the system simulator i mentioned above.

greets claas

That frame rate seems surprisingly low, even for an Intel G915 graphics card. I suspect that you may be running with the Microsoft software OpenGL drivers; I'd recommend downloading and installing the Intel OpenGL drivers:

http://www.intel.com/support/graphics/i ... 011906.htm

(though it's possible that you may have to get them from your laptop manufacturer instead.)

As for accuracy of planet orbits and orientations, it depends on that data source that you're using. By default, Celestia uses the VSOP87 theory to compute planet positions; Celestia uses enough terms to give positions to within 1 arcsecond. See here for more details:

http://en.wikipedia.org/wiki/VSOP87#VSOP87

Note that since Celestia doesn't use all the VSOP87 terms, 1 arcsecond accuracy isn't guaranteed for times in the distant future or past.

If you need more accurate planet positions, you can configure Celestia to use the JPL DE405 ephemeris for the planets, Pluto, Sun, and Moon:

http://en.wikibooks.org/wiki/Celestia/JPL_Ephemerides

As for orientation, Celestia 1.5.1 assumes that planets are rotating uniformly about a fixed axis. This gives good results for times near the present, but there are problems when extrapolating far into the past or future. In Celestia 1.6.0, we've switched to using the IAU/IAG rotational elements for the planets. As far as I know, these are the standards for planet orientation with the exception of the Earth. The Earth rotation model in Celestia 1.6.0 accounts for precession but still assumes a constant rotation rate. Without a better model for universal time, events such as ancient eclipses can be many degrees off from their reported locations. If this is of concern to you, you should configure Celestia to use a SPICE kernel for Earth rotation (this is supported in the 1.6.0 code only.)

--Chris