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Run Specview In Applet Mode

You don't have to install Specview in your computer, you can just run it in your Web browser as a Java applet.

Caveat: the applet does not run the most recent version of Specview (it runs version 2.14.4). It is recommended that you install the application version (here) in case you need to do heavy-duty work.

Clicking on the "Demonstration" link below will download the applet version of Specview. It automatically downloads and displays a number of spectrograms from the nuclear region of the NGC3516 Seyfert galaxy obtained with a variety of instruments.


To run an "empty" (no pre-loaded data) version of the Specview applet, use the "Run" link instead.


The applet requires that your Web browser be equipped with version 1.6 of the Java Plug-in.

The applet behavior depends on how you answer to the security query dialogs:

Answering "Yes" or "Accept", to the dialogs, the applet will be able to read and operate with files in your local file system, as well as connect to Virtual Observatory sites and STScI sites and download data from them. You will also be able to perform operations, measurements and analysis with any files you have on your local file system, and write results back to your local file system. Even a preferences file, if existent, will be accessed and used to configure the Specview applet. Thus the applet will perform in a very similar way as the application version of Specview would.

Answering "No" still enables the applet to work, but it will not be able to perform any function that requires access to the local system or the network.

Version 2.14.4 of Specview was tested under the following configurations:

OS Browser
Windows XP Home Internet Explorer 6.0
Windows XP Home Firefox
Windows XP Home Opera 9.02
Windows XP Pro 2002 Netscape 7.0
Windows XP Pro 2002 Internet Explorer 6.0
Windows XP Pro 2002 Mozilla 1.7.2
Mac OS X 10.6 Safari 4.0.3

Known Bugs

At this point there are a few issues related to graphics and memory management implementation in some of the browser / Java plugin combinations that can be run on different platforms/OSs.

Cross Hair Cursor May Trash Screen

Under some circunstances, the cross-hair cursor may misbehave and leave garbage on the screen. This is caused by bugs in the graphics XOR mode implementation in some plug-in/browser combinations. If that happens, you can force a redraw operation by either resizing the browser window, or minimizing and then maximizing it.

Cross Hair Cursor Won't Appear

It may happen that the cross hair cursor fails to appear on screen. This seems to be related to the different ways each browser implements threads of control. One can fix the problem by displaying a different spectrogram (use the "Display" or "Coplot" menu) and then displaying the original spectrogram again.

Note that under MacOS the cursor drawing is tuned off. Under that OS, cursor drawing didn't used to work at all. Recent updates to MacOS and Specview code fixed the problem. A future update of the applet will have the cursor drawing back on.

Out-of-memory Errors

With very large files such as IUE echelle, STIS echelle and ISO LWS, or when many files are downloaded from the Virtual Observatory interface, OutOfMemory conditions may happen. This is caused by intrinsic limitations in the amount of memory available for the Java plugin that runs under the browser control. There are two solutions for these cases:

One can increase the memory available to the Java plugin. See here how to do it.

Alternatively, one can resort to the application version of Specview. It can be downloaded from here.