Obtaining and Installing

How to acquire and install CASA

Go directly to the CASA Download Page

Obtaining CASA

CASA is available for the following operating systems:

  • Linux
    • Red Hat 6
    • Red Hat 7
  • Mac OS
    • macOS 10.13 (High Sierra)
    • macOS 10.12 (Sierra)

The above OSs are the ones that we use to test the CASA package. Other flavors of Linux may work, too. 

The latest and previous releases can be downloaded from our CASA home page: http://casa.nrao.edu, following the ’Obtaining CASA’ link (direct link: http://casa.nrao.edu/casa_obtaining.shtml).

Installing CASA


To install CASA for Linux, we have packaged up a binary distribution of CASA which is available as a downloadable tar file. We believe this binary distribution works with most Linux distributions.

We do not currently have a distribution designed for end users who wish to do C++ development using CASA.

Simply download and untar the distribution

tar xzvf casa-release-##version##.tar.gz 

all executables, including casa are in the casa-release-##version##/bin directory.


You do not have to have root or sudo permission; you can easily install CASA, delete it, and move it, and it works for many versions of Linux.

You may also want to include the executables in your path, i.e.

export PATH=$PATH://casa-release-##version##/bin 

for bash or

set path = ($path //casa-release-##version##/bin)

for csh shell environments.

The one caveat is that CASA on Linux currently will not run if the Security-Enhanced Linux option of the linux operating system is set to enforcing. For the non-root install to work, SElinux must be set to disabled or permissive (in /etc/selinux/config) or you must run (as root):

setsebool -P allow_execheap=1

Otherwise, you will encounter errors like:

error while loading shared libraries: /opt/casa/casa-20.0.5653-001/lib/liblapack.so.3.1.1: cannot restore segment prot after reloc: Permission denied

The non-root installation is thought to work on a wide variety of linux platforms. Check the list of operating systems at the top of this page for the officially supported OSs. Other platforms may work, too, but we do not regularly test those.

Unsupported platforms

The non-root install may work on other platforms not listed, please let us know if you find that this binary distribution of CASA works on other linux platforms.

Also note, that the plotting tasks, such as plotcal, are the ones that typically give problems for new platforms, so a check of these after attempting an unsupported platform installation is advisable.


CASA for Macintosh is distributed as a self-contained Macintosh application. For installation purposes, this means that you can install CASA by simply dragging the application to your hard disk. It should be as easy as copying a file.

  1. Download the CASA disk image for your OS version from our download site
  2. Open the disk image file (if your browser does not do so automatically).
  3. Drag the CASA application to the Applications folder of your hard disk.
  4. Eject the CASA disk image.
  5. Double-click the CASA application to run it for the first time. If the OS does not allow you to install apps from non-Apple sources, please Change the settings in "System Preferences-> Security & Privacy -> General" and "Allow applications downloaded from: Mac App store and identified developers".
  6. Optional: Create symbolic links to the CASA version and its executables (Administrator privileges are required), which will allow you to run casa, casaviewer, casaplotms, etc. from any terminal command line. To do so, run 


    from a CASA prompt. (In CASA 4.2.2 and earlier you will be prompted to update the symlinks on double clicking the Application)
  7. Optional: To update the data repository, run 


    from the CASA prompt. (In CASA 4.2.2 and earlier the data repository will automatically update upon the start of CASA)

Multiple installations of CASA

If you want to have more than a single version of CASA in the Application folder, simply rename the CASA.app to some other name (e.g. CASA-version.app). When you double click on any available version, that specific one will be launched. And if you recreate the symbolic links as explained above, the casa, casaviewer, casaplotms, etc. executables will then be pointing to that version. Switching CASA versions then comes down to double click the wanted Application and recreate the symbolic links if desired.



  • If you see error messages about "dbus" and "launchctl", you may have to unload previous dbus sessions:

    launchctl remove org.freedesktop.dbus-session
    launchctl remove org.freedesktop.dbus-system

  • Versions after 12115 are 64bit only and will not work on older mac intel machines
  • Apple Gatekeeper may indicate that the CASA application is not from an identified developer. If this happens, follow the instructions here or change the your Security & Privacy settings as described here to bypass the Gatekeeper check.


If you encounter difficulties, please see our list of Known issues or consult the CASA helpdesk or ALMA helpdesk, where we maintain knowledgebase articles and where you can get in touch with us. You may also consult the NRAO Science Forums to discuss any CASA issues amongst CASA users.

If you want to be kept up to date about CASA, please subscribe to our CASA mailing lists.