Celestia Forums

Just as a note, it would be entirely possible for the Celestia dev team to release the Celestia source under a second license (non-GPL) for the use of people who wanted to include it in another non-GPL product. Not that I see that as likely, though, but I though I'd point it out. Doing so would in n...

You're right, the MKSPK documentation doesn't mention SPG at all. Unfortunately, NAIF seems to suck at documenting things in obvious places... From the intro to 'geophysical.ker': The mkspk application needs the data in this kernel to produce type 10 SPK segments based upon the two-line element sets...

I know that a number of people (me included) have been wanting a way to get improved satellite orbits into Celestia for a long time, using TLEs and the SGP4 model to do it. Here's an outline of how to do it, /without/ having to implement the SGP4 model in Celestia. This should work fine with any rec...

In the middle of messing with other things, I've come up with a workaround/solution for the strange way the Sun's orbit is shown. :) This /is/ the Sun's actual orbit around the barycenter for the period from 1599 to 2201, from the latest JPL ephemeris. Wierd, huh. http://img511.imageshack.us/img511/...

Agreed--CCDM is apparently not a reliable way to find bound pairs. There may be some other information in the data set that will help us figure out which stars are actually bound and which are merely optical doubles. Could proper motion be used as a criterion for deciding whether the stars constitu...

I'd typed a nice long detailed message about this onto the Bug thread, but of course phpbb didn't post it for me ('post mode not defined', or some such error) and it was gone when I hit the back button. Once again I get to curse and remind myself to copy long posts to the clipboard before hitting th...

One feature that should be very simple to implement, and would be very nice, would be to allow objects defined in ssc files to have multiple names, like ones from stc and dsc files.

That link will become outdated before too long, since it's to the top page. Here's the actual article. http://www.nasa.gov/mission_pages/mars/news/mgs-20061206.html There are two locations cited, and if you look at the hi-res images it seems pretty clear that there was definitely flowing liquid of s...

http://cdsweb.u-strasbg.fr/viz-bin/Cat?I/239

Hipparcos gives BT and VT magnitudes, as well as B-V and V-I colors.

Thanks for the effort you put into keeping these up to date, but I do have a suggestion. Just to make it a little easier to keep things in sync, would it be too much trouble for you to include the version # somewhere in the header in each file? Poormoons says it's not compatible with any version of ...

Some people have been asking about ISS elements recently. Here ya go. :) Progress cargo module M-50 (NORAD 28399, COSPAR 2004-032A) was launched on Aug 11 as flight ISS-15P to the International Space Station. Tomorrow, Nov 17, the engine of the Progress module will be used for a reboost burn for the...

In a double system, the barycenter is going to be at the same place as the L1 point, and orbits around the L1 point are always unstable. Think about the gravitational pull as a potential field and you'll see why. When the moon is closer to one planet than the other, it wil no longer feel a net force...

That phase diagram kinda sucks. :) Not really, but it's just a sketch. Here's one a better one I stole from lsbu.ac.uk http://www.lsbu.ac.uk/water/images/phase.gif You don't need to worry about the Roman numerals, because you'll never see anything like those kinds of pressures on Mars. They are labe...

Edit starnames.dat, and add the Bayer numbers for the dimmer stars in each constellation.

Wow, look, 357 Kentauri, guess it's in Centaurus.

No coding needed.

Probably not a good idea if you want a realistic distribution. Both Hipparcos and the celestia database extraction procedure have an inherent selection bias, and that'll show up in your data. For example, you'll be missing lots of dim stars.

Out of curiousity, I actually sat down and tried to handwave my way through this. I just used simple geometry, so don't nitpick. :) Given the surface area of a 430 ly sphere, and the cross sectional area of the Earth, about 1.6x10^-24th of the released energy would pass through the Earth. Now, type ...

I've verified that these errors are in the 2x10^6 star database. They're probably all in the normal database as well, since they're really errors in the Hipparcos catalog. My source for these was the error list in the I/239 (Hipparcos and Tycho catalog) directory on Simbad. The following M0 stars ar...

Henrik, I trust you realize that if you insist on such an interpretation, many Addons (most of mine, for example) will have to be withdrawn from public availability. As I pointed out earlier, many are derivative works based on images which are not and cannot become GPL'd. I addressed this point in ...

Well, they track everything they can that's worth tracking. Object 16013 is a screwdriver that was dropped during an eva on STS 51. The problem is that as altitude increases they can only see larger objects, but the smaller objects they can see at lower altitudes are in less stable orbits. So, they ...

No, as far as I know Horizon's won't do that, but it wasn't what I meant. I guess I was unclear. What I meant was that for a particular encounter, say the first Europa flyby, you could generate a Europa-centric empheris with, say, 60 arcsecond resolution (that's the smallest interval), look at that ...