1. Download and install version v4.3 or higher of the Fv program on your computer. (The version of Fv that is included in the April 2005 release of version 6.0 of the HEASARC's HEASOFT package will not work). Make a note of the full directory path to the fv executable because this will be needed in the next step.

2. Configure your web browser to user fv as a helper application. To do this, click on this 'Test Hera' link and carefully follow these instructions:
   • The first time you click this link a brower window should appear that asks what you want to do with files of type XHERA or text/x-hera.
   • Select the "Open with" option, and use the "Browse" or "Choose" button to find and select the previously installed fv executable file.
   • Also select the option box to "always do this automatically" the next time a file of this type is opened, if your browser provides that option.

If these steps have been performed successfully, then when you click on the above 'Test Hera' link again, a new window should be displayed confirming that you have successfully setup your browser to use fv as a helper application.

If for some reason you need to reset the path to the fv executable, follow these instructions, depending on your browser:

• Firefox: under the Edit -> Preferences -> Downloads menu item, click on "View & Edit Actions", select the line associated with HERA, and click the 'Remove' button.
• Mozilla/Netscape: under the Edit -> Preferences menu item -> Helper Applications, select the line associated with text/x-hera, and click the 'Remove' button.

  You should then be able to click on the above 'Test Hera' link, and enter the new path to the fv executable.