Celestia Forums

Hello,

Is there any way of telling where certain nebula and galaxies should be located in space? And how do I represent this in Celestia? The "dsc" file is a little puzzling.

Christoria,

The location information in DSC files is specified using standard astronomical values in the J2000 coordinate system.

RA = Right Ascension in fractional hours
Dec = Declination in fractional degrees
Distance = distance from solar system in Light Years
Radius = radius of object in Light Years

A confusion factor is that in STC files
RA = Right Ascension in fractional degrees

It'd be nice if both types of catalog files used the same units, but even professional astronomers seem to be inconsistant in whether they specify RA in hours or degrees. *shrug*

Does this help?

Absolutely! Thank you. Copied, pasted and applied.

Now, how do I find out where all these galaxy and nebula are, so I can put the values into a "dsc" file. A lot of them are already included in Celestia and add-ons, but some are not. Especially the newest ones with some truely incredible pictures.

Christoria,

Precise RA and Dec coordinates for most astronomical objects can be obtained from the Simbad server at http://simbad.u-strasbg.fr/sim-fid.pll Distances often are more problematic. Searching the Web with Google is usually the best way to find them.

Bear in mind, however, that the coordinates of an astronomical object may be quite a distance from where you have to center a picture so that it matches its actual position on the sky. I often use pictures downloaded from http://virtualsky.org/ to get the alignment right.

Please take a look at the Web page http://www.lns.cornell.edu/~seb/celestia/billboard.html for a partial description of the methods that I use.

Thanks again. I'll do that. You've been very helpful.