CASA 6.6 is based on Python 3, and available either as a downloadable tar-file distribution with Python environment included, or as a modular version that can be installed with pip-wheels.
Manual processing can be done with any CASA version, but ALMA and VLA pipelines may differ and are not always included, so download the correct CASA version for pipeline use.
CASA is only fully validated against the operational configuration of NRAO instruments (currently RHEL8/Python 3.8).
The CASA versions listed above are built on specific versions of Linux RedHat and Mac OS, but they are expected to work for multiple LINUX and Mac computer operating systems, including Mac OS 13 (CASA 6.6.0) and certain Ubuntu versions. See the OS compatibility matrix in CASA Docs, or see 'Version Support' below for more details.
*Note for VLBA:
VLBI functionality has been implemented in CASA for the processing of VLBI continuum and spectral line observations, based on development by the CASA-VLBI group at JIVE (see this article). For NRAO's Very Long Baseline Array (VLBA), CASA may be used for calibrating and imaging relatively simple VLBA data sets. Do not use CASA if your VLBA project involves polarimetry, astrometry, low frequencies (< 4 GHz), or data from before December 2009. Also, do not use CASA if your project requires fringe-rate mapping or the use of antab files. See the CASA VLBA Calibration and Imaging page for more details.
CASA 6 can optionally be installed through modular pip-wheels, with the flexibility to build CASA tools and tasks into a customized Python environment. Instructions on how to install the pip-wheel version of CASA 6 can be found in CASA Docs: CASA 6 Installation
The modular pip-wheel version is not yet used in production by ALMA and VLA, and does not include any pipelines.
For the use of pipelines and recommended CASA+Pipeline versions, please consult the ALMA pipeline and VLA pipeline webpages.
Release information for previous casa versions can be found in (for CASA 6.2+), or in the archival version of archival version of CASA Docs (CASA 5.0 - 6.1).
Pre-release versions of CASA can be found here (see also this download through Google Drive). Pre-release versions reflect ongoing CASA development and are not supported. Use at your own discretion.
CASA 6.5 is fully validated against the operational configuration of NRAO instruments, which currently is Linux RHEL8/Python 3.8.
Automated verification tests have been performed for a number of Operating Systems and Python versions. The following table in CASA Docs gives an overview of the automated testing done for CASA.
Manual package testing has been performed for the OS version that are included in the download table at the top of this page.
Other systems on which we expect CASA to work, including certain versions of Ubuntu, are listed in the compatibility matrix on CASA Docs. CASA accepts bug reports for all combinations of OS and Python that are listed there.
Mac M1: CASA for Mac OS is officially supported for x86 Intel chips. Nevertheless, automated testing shows that CASA tasks and tools work on M1 machines. We therefore recommend that users with M1 machines should use the OS 12 x86 packages or pip-wheels to run CASA in those machines, and report any problem to casa-feedback_at_nrao.edu.
Other LINUX: CASA may also work on other flavors of Linux, but this is at the discretion of users. Some tips from the community can be found here.
NRAO has installed a suite of CASA and pipeline versions for local users, visitors, and users who request remote access to NRAO machines. More information on running CASA locally at NRAO can be found here.
To efficiently run CASA, a balanced hardware configuration regarding memory, processing
power and file I/O may be required. Recommendations on the CASA hardware requirements for VLA and
ALMA data can be found on this 'Hardware Requirements' page.
DISCLAIMER: CASA now collects usage statistics including task execution timings
and crash reports. This data will be periodically sent back to NRAO to
guide future priorities and decision making. All collection is anonymous and contains no scientific or personal data. For more information, or instructions on how to disable telemetry recording, see CASA Docs
Linux
Mac
The above CASA versions can also be downloaded from our 
(for CASA 6.2+), or in the archival version of archival version of CASA Docs (CASA 5.0 - 6.1).
