Contents

Overview

The starfield simulation is an interesting part of this site. The default animation uses about 9,000 stars from the Yale Bright Star Catalog. For an animation running in a browser, that's an appropriate number of stars, and the results do demonstrate the proper physics.

But for a more realistic result, closer to what you would actually see, you need to use more stars - many more stars, even millions. Since an animation using that many stars would not work well in a typical browser, a small desktop application (implemented in the Java programming language, version 1.7.0) has been created for generating such images from large star catalogs. The software is simple, and consists of a single dialog, where you input various parameters, and then generate a single image file. No animation is created, just a single image file. (With the number of stars in the millions, it can take several minutes to generate a single image.)

Download One or More Star Catalogs

To use this software, you also need raw data from a star catalog. As is, the software will work with three commonly used astronomical catalogs. (Note for progammers: adding a parser for some other catalog isn't difficult, and would usually take about 15 minutes or so.) The three catalogs are available here (look for the FTP links at the top):

You don't have to download all of these if you don't want to, but you will need at least one of them. The Tycho-2 catalog gives the most impressive result, but it takes longest to download. Save the data files for each star catalog in some convenient, separate location on your computer. If the data files are zipped, you'll need to unzip them.

Here's an example of how you might arrange the catalogs and their data files: 

C:\astro-cat
  \henry-draper
    catalog.dat
  \tycho-2
    tyc2.dat.00
    tyc2.dat.01
    ...
    tyc2.dat.18
    tyc2.dat.19
  \yale-bright-star-cat
    catalog.txt
The above is just an example. You can place these data files anywhere you want. However, you'll need to ensure that the data files for each star catalog are placed in their own separate directory by themselves, with no other extraneous files. The names of the files don't matter, but note that if you change the name of a data file to end with '.ignore', then this application will ignore it. (This is useful when experimenting with different data sets.)

Download the Software

There are two items you can download:

Run the Software

To run the software, you'll need Java installed on your computer. (Most personal computers already have it installed.) Here's an example of launching the application as a graphical tool. This example assumes that you've put the unzipped contents of starfield-binary.zip in C:\TEMP>. 
C:\TEMP\> dir /b
jgoodies-common-1.7.0.jar
jgoodies-forms-1.7.2.jar
starfield.jar

C:\TEMP> echo %JAVA_HOME%
C:\jdk1.7.0

C:\TEMP\> C:\jdk1.7.0\bin\java -jar starfield.jar

(If java is on your path, then you may use this style.)
C:\TEMP\> java -jar starfield.jar
This will launch the application, which consists of a single dialog:

When the application is running, you'll see that each input field has an explanatory tool-tip, which pops up when the mouse is hovering over the input field. For more information, please see the documentation on input parameters.

Here's a second example, but this time the tool is run as command-line tool only, with no graphical interface. Note that there are 11 parameters passed to the hirondelle.starfield.Main class. 

C:\TEMP\> dir /b
jgoodies-common-1.7.0.jar
jgoodies-forms-1.7.2.jar
starfield.jar

C:\TEMP> echo %JAVA_HOME%
C:\jdk1.7.0

(this command is really on a single line)
C:\TEMP\> java -cp starfield.jar -Xmx512m hirondelle.starfield.Main 0.993 5.0 
C:\astro-cat\yale-bright-star-cat YALE_BRIGHT_STAR_CATALOG 
C:\temp\test.png STEREOSCOPIC 800 1 0 90 0

Detailed Documentation

For more detailed information, please see the application's javadoc.