A (not so) Brief Introduction to Celestia Addons Part 5 (3rd edition)

5: Installing an Addon of Stars and Planets.

Many of Rassilon's creations are available on the Web at http://www.shatters.net/~rassilon/. This particular Addon is available at http://www.shatters.net/~rassilon/NGC2244-systems_i.zip. NGC 2244 is the designation for the Open Cluster of stars in the middle of the Rosette Nebula. The Nebula itself is NGC 2237.

This Addon was designed assuming that you already have installed the Addon described in section 4 above as well as a "Globular Cluster" generator. Installing this Addon by itself has some potential problems which can be used to illustrate how Celestia supports Addons.

Katalina is Rassilon's name for an imaginary star which is the primary content of this Addon. This star name needs to be made known to Celestia. Briefly, the following steps will make that happen:

5.1: Edit \data\starnames.dat

Note: If you have a version of Celestia released after v1.3.0, like v1.3.1pre3, you don't need to modify starnames.dat. You can include the star's name in the STC file itself.

5.2: Create the directory tree for \extras\addons\NGC2244\ (This makes it easy to keep track of NGC2244's pieces.)

5.3: Create \extras\addons\NGC2244\katalina.stc. (This tells Celestia where to draw the star.)

5.4: Copy NGC2244-katalina.ssc from the Zip file to the folder \extras\addons\NGC2244\ (This describes all the planets around the star.)

5.5: Copy all of the picture files that are in the Zip file in the directory \textures\medres\ to \extras\addons\NGC2244\textures\medres\.
(These images of the planets' surfaces are the artwork that Rassilon spent a lot of his time creating.)

5.6: Then you can GoTo the star and see its planets.

5.1: Editing `starnames.dat`

First some background:

Rassilon defined the planets that orbit around Katalina in the file NGC2244-katalina.ssc, and he used the star name "Katalina" everywhere in that file. So that name has to be taught to Celestia.

Celestia uses "Hipparcos numbers" to keep track of stars. Hipparcos numbers are numbers assigned by the astronomers who used the Hipparcos Satellite to measure the distances to many stars.

Imaginary stars like Katalina have to be given fake Hipparcos numbers in Celestia. Usually people use numbers between 300000 and 600000.

In order for Celestia to know which star number has which name, both its number and its name have to be added to Celestia's file \data\starnames.dat.

starnames.dat is a text file. It doesn't have any special binary codes in it. As a result, you can use either Notepad or Wordpad to edit starnames.dat.

Wordpad is usually a better choice because starnames.dat doesn't use the standard Windows method of using the two characters [carriage-return] [line-feed] to separate lines from one another. It just has [line-feed] between the lines, and so Notepad doesn't show the file right.

Be careful. though. Celestia gets all of its starnames from starnames.dat. You might want to copy it somewhere else to save it in case it gets damaged. You can copy back the one you saved if something goes wrong.

As Rassilon wrote in the README in the Zip file, you have to add this next line to the very end of \data\starnames.dat:
500506:Katalina

You can use the START menu, RUN item to start Wordpad and then use Wordpad's "file open" menu to get to starnames.dat

5.2: Creating the directory tree for NGC2244

If you haven't already, create a directory (folder) within Celestia's extras directory which has the name addons. This will let you move all of your Addons at once by moving just this one directory.
Within the addons directory, create a directory for each Addon when you install it. For example, you might create the NGC2244 directory.
Within the NGC2244 directory, you must create the directories for its models and its surface textures: create the directories models and textures Within the textures directory, create the directory medres. (The lores and hires directories aren't needed for this particular Addon.)

When you've created the new directories, your directory structure might look something like this:

5.3: Creating the STC file

Rassilon buried the definition for the star 500506 in the middle of one of his very big star catalogs. The Readme says you can delete those catalogs if you don't have his Globular Cluster Addon. But if you do that, you can't find Katalina.

Here's a simple .STC file that defines just the star that is named Katalina. Create this file in the directory \extras\addons\NGC2244\. You can use your favorite editor to create it. Notepad is fine. Wordpad is OK, too.

#######################
#katalina.stc
#######################

# HIP 500506
500506 {
	RA  98.02484576
	Dec  5.04107509
	Distance  5500.3959
	SpectralType "G0Ia-O"
	AppMag 15.00 # Radii: 1.47270096432767
} 
#######################

katalina.stc

If you're using Celestia v1.3.0, its STC files can only include the Hipparcos index number. Names have to be added to the file starnames.dat.

If you're using Celestia v1.3.1pre3 or later, its STC files can include both a star's Hipparcos index number and its name.

The star's name must follow the Hipparcos number, be enclosed in quotes, and come before the first "{". More than one name can be specified between the quotes if they're separated by colons (:).

For example, here's how you could define Katalina as the name for the star HIP 500506:

500506 "Katalina" {

5.4: Copy `NGC2244-katalina.ssc`

\extras\addons\NGC2244\

Note: NGC2244-systems_i.ZIP includes an \extras\ directory which contains all of its catalog files. Those files all must be moved into the Addons directory itself, \NGC2244\, and the folder \NGC2244\extras\ should be deleted. This is an older Addon which was created before the new directory layout became possible.

5.5: Copy all of the picture files

\textures\medres\

\extras\addons\NGC2244\textures\medres\

Once you've changed starnames.dat, created katalina.stc, and put the other files in the right directories, your directory structure should look something like this: