How to install CASA on AWS

This guide explains how to install the monolithic CASA distribution locally for an individual user on AWS, without requiring a system-wide installation.

Related

• How to start an interactive compute node on AWS

• Accessing the clusters (Confluence)

• CASA Guides

Prerequisites

• An account on AWS and access to the head node.

Steps

Note

If you want CASA GUI support, ensure that you have enabled the -Y flag when connecting to the head node via ssh.

1. Create and enter a directory where the CASA tar file will be downloaded and unpacked. In this example, we use $HOME/software/casa:

   mkdir -p "$HOME/software/casa"
   cd "$HOME/software/casa"
   

2. Navigate to the official CASA download page and find the latest stable release for Linux. At the time of writing, the latest version is CASA 6.7.3. So the command would be:

   wget -c https://casa.nrao.edu/download/distro/casa/release/rhel/casa-6.7.3-21-py3.12.el9.tar.xz
   

3. Unpack the downloaded tar file:

   tar -xvf casa-6.7.3-21-py3.12.el9.tar.xz
   

   This should create a directory called casa-6.7.3-21-py3.12.el9 containing the CASA executables under bin. The tarfile can be deleted after successful unpacking.

4. CASA ships with its own python and pip aliases that point to the casa executable. To avoid confusion, instead of adding casa-6.7.3-21-py3.12.el9/bin to your PATH, we recommend creating symbolic links to specific executables in ~/.local/bin.

   ln -s "$HOME/software/casa/casa-6.7.3-21-py3.12.el9/bin/casa" "$HOME/.local/bin/casa"
   ln -s "$HOME/software/casa/casa-6.7.3-21-py3.12.el9/bin/mpicasa" "$HOME/.local/bin/mpicasa"
   ln -s "$HOME/software/casa/casa-6.7.3-21-py3.12.el9/bin/casaviewer" "$HOME/.local/bin/casaviewer"
   

   Replace casa-6.7.3-21-py3.12.el9 with the actual name of the unpacked CASA directory if the version is different.

5. Ensure that ~/.local/bin is in your PATH. You can check this by running:

   echo $PATH
   

   If ~/.local/bin is not in your PATH, you can add it by adding the following line to your shell configuration file (e.g. ~/.bashrc):

   export PATH="$HOME/.local/bin:$PATH"
   

   After adding this line, reload your shell configuration:

   source ~/.bashrc
   

6. Before starting CASA for the first time, ensure that $HOME/.casa/data exists so that a minimal data repository can be downloaded by CASA to this standard location (if you prefer a different location, start casa without creating this directory and follow the instructions in the displayed error message):

   mkdir -p "$HOME/.casa/data"
   

   CASA will download a minimal data repository to this location on the first run.

Verification

Check that the casa command is available:

which casa

This should print something like:

/home/<your-username>/.local/bin/casa

Start CASA:

casa

CASA should start and drop you into the CASA command prompt.

Note

CASA will attempt to open the GUI logger by default. If the -Y flag was not set when connecting to the head node via ssh, CASA IPython interpreter will still work but GUI tools will not be available. Alternatively, you can start CASA with the following options to disable the GUI logger and log to the terminal instead:

casa --nologger --log2term

Warning

We do not recommend running computation-intensive CASA tasks on the head node, including interactive tasks such as plotms. Make sure you are on an interactive compute node before running CASA on any large data set.

FAQ

Q: Why install CASA this way instead of using a system-wide module?

A: This method is intended for occasional local use, testing, debugging, and interactive inspection of data products. The monolithic CASA distribution is not always efficient for server use or large data sets; tools such as plotms can be slow with large Measurement Sets, sometimes taking many minutes to display data even locally, and may be unstable or crash unexpectedly. For routine data processing or large-scale data analysis, use more targeted data processing tools and pipelines available on AWS. For quick plotting of large data sets, use tools such as shadems available on AWS.

Q: Can I install multiple CASA versions?

A: Yes. Keep each CASA version in its own directory under $HOME/software/casa and update the symbolic link in ~/.local/bin to point to the version you want to use.