Install CIAO 4.18 and CALDB 4.12.3

Installation instructions

Please check the system requirements for installing and running CIAO.

Install CIAO using:

• the ciao-install script
• the conda create command
• the .dmg disk image file (macOS only) (16 Dec 2025)

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Use ciao-install script if …

• You are unfamiliar with conda

• You only want to install a few extra packages (like astropy and SciPy) which can be done with the pip tool that comes with CIAO. (For more complex packages it may be easier to install CIAO with conda.)

• You want to install the CIAO and/or Sherpa source code

For more information see the Installing CIAO 4.18 Using the ciao-install Script thread.

Use conda create if …

• You are already familiar with conda, virtualenv, or other virtual environments.

• You need to install specific version of third party applications such as Numpy, Matplotlib, or SciPy to ensure compatibility with other packages such as astropy.

The conda package manager is available from several different sources with different licensing requirements. It is the users' responsibility to read and adhere to the Terms of Service for their conda installation. The miniforge version of conda is compatible with CIAO.

For more information see the Installing CIAO with conda thread.

Use the CIAO .dmg disk image if ...

• You are on macOS: either Intel/AMD/x86 or Apple Silicon/ARM/M1/etc.

• You have permission to install in the /Applications folder.

• You want to install all packages: CIAO including the contributed Scripts, Sherpa, DS9, MARX, and the main Chandra CALDB files.

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Using SciServer

Alternatively, CIAO has been pre-installed on the SciServer platform by the High Energy Astrophysics Science Archive Research Center (HEASARC). While the CXC does not manage the installation, we have provided some instructions for running CIAO on SciServer.

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