7 Invoking TOPCAT

Starting up TOPCAT may just be a case of typing "topcat" or clicking on an appropriate icon and watching the Control Window pop up. If that is the case, and it's running happily for you, you can probably ignore this section. What follows is a description of how to start the program up, and various command line arguments and configuration options which can't be changed from within the program. Some examples are given in Section 7.4. Actually obtaining the program is not covered here; please see the TOPCAT web page http://www.starlink.ac.uk/topcat/.

There are various ways of starting up TOPCAT depending on how (and whether) it has been installed on your system; some of these are described below.

There may be some sort of short-cut icon on your desktop which starts up the program - in this case just clicking on it will probably work. Failing that you may be able to locate the jar file (probably named topcat.jar, topcat-full.jar or topcat-lite.jar) and click on that. These files would be located in the java/lib/topcat/ directory in a standard Starjava installation. Note that when you start by clicking on something you may not have the option of entering any of the command line options described below.

Alternatively you will have to invoke the program from the command line. If you have the full starjava installation on a Unix-like operating system, you can use the topcat script, which should be in the java/bin/ directory. So if that directory is on your path, you can write:

   topcat [java-args] [topcat-args]
In this case any arguments which start -D or -X are assumed to be arguments to the java command, a -classpath path defines a class path to be used in addition to the TOPCAT classes, and any remaining arguments are used by TOPCAT.

If you don't have the starjava Unix installation then to start from the command line you will have to use the java command itself. The most straightforward way of doing this will look like:

   java [java-args] -jar path/to/topcat.jar [topcat-args]
(or the same for topcat-full.jar etc). However NOTE: using java's -jar flag ignores any other class path information, such as the CLASSPATH environment variable or java's -classpath flag - see Section 7.2.1.

Note that Java Web Start can also be used to invoke the program without requiring any prior download/installation - sorry, this isn't documented properly here yet.

The meaning of the optional [topcat-args] and [java-args] sequences are described in Section 7.1 and Section 7.2 below respectively.