Can I use a newer version of ds9 than the one packaged with CIAO?

In short, yes. There is a simple way to do so and a few important caveats associated with upgrading the imager, all of which are described in this FAQ.

When a CIAO release is being prepared, the most recent version of ds9 available is used in testing and then packaged with the software. Since updates to ds9 are released on a shorter timescale than CIAO, users may wish to upgrade independently of CIAO to take advantage of new features and bug fixes.

Users can download a different version of ds9 from the SAOImage ds9 website. macOS users should be sure to select the "X11 (requires Xquartz)" version appropriate for their hardware (intel or Apple silicon, eg M1/M2/M3 chips). After the file has been downloaded and uncompressed (using the gunzip command), the file(s) should be moved to the $ASCDS_INSTALL/imager/ directory. For Linux this will be the single ds9 executable. For macOS this will be both the ds9 executable and ds9.zip package; do not unzip ds9.zip!

Caveats

• We do not guarantee that CIAO will work flawlessly with a newer release of ds9! The software team only tests the version of ds9 included with CIAO; it is possible that subsequent changes to the imager may cause unexpected problems in the CIAO software. Users who experience problems may contact the CXC HelpDesk, and we will do our best to assist you.

• The preferences set in ds9 are stored in a file called $HOME/.ds9/ds9.${version}.prf; where ${version} is the version of ds9. The Preferences section of the ds9 manual contains more information on avoiding this problem when supporting multiple versions of ds9.

For more general information on how to use ds9, refer to the Using SAOImage ds9 thread.