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Last modified: 7 December 2023


System Requirements

CIAO is supported on a number of operating systems, which are listed on the Platform Support page. Certain system requirements are necessary to successfully install and run CIAO.

Installation requirements: conda

When using conda to install CIAO, the conda command-line tool must be present, and be at least version 4.7.6:

$ conda --version
conda 4.10.3

If the command does not exist then the miniconda package can be installed from the Anaconda website, and if the version is too low then it can be updated with

$ conda update conda
Installation requirements: ciao-install

For CIAO installation by the ciao-install script, available from the download page. This script requires bash to run it and curl to download the necessary files.

Memory and Disk Space

Chandra data files are large, which implies that certain processing and analysis operations will work more efficiently when they have access to large amounts of RAM. We recommend a minimum of 4Gb main memory. A full CIAO installation, including the background calibration files will require ~15Gb of disk space. The disk space for individual observations varies from a few megabyte to several gigabytes depending on the target as well as the exposure time and instrument configuration.


Pre-built binaries for CIAO 4.16 are built for Linux on Red Hat Enterprise 8 machines. These are expected to be compatible with most recent Linux distributions, but may not work with old versions.


X11, the X window system.

Apple macOS

Pre-built binaries for CIAO 4.16 for macOS were built on macOS 11 (Big Sur) Intel chip and separately for the [New]M1 chip. They are compatible with newer versions of macOS through macOS 14 (Sonoma) and the M1 chip build is compatible with M2 and M3 chips.


X11 must be installed from the XQuartz website. Users must be using XQuartz version 2.8.4 or newer.


CIAO requires users have the Apple's Xcode tools installed on OSX/macOS. These tools are needed during the installation process to configure the programs to run on users machine. If it is not already installed, you can start the install process by opening a terminal and running this command:

$ xcode-select --install