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Last modified: 20 December 2022


Bugs: CIAO installed using conda

Table of Contents



macOS users must use the Intel x86-64 version of conda

On macOS, support for the ARM64 architecture is via Rosetta2 emulation. This means that you must use the Intel x86-64 version of conda to install CIAO, ds9, and Sherpa.

If you try to use the ARM64 version then you will find that the packages are missing and the list of current channels will include

List of known packages CIAO is incompatible with

  • CIAO and StSCI's astroconda which fail due to version incompatibilities in the CFITSIO library.
  • There is a conflict between CIAO and HEASARC's XSPEC package. Users must
    1. First, initialize their HEASARC environment

      $ export HEADAS=/soft/lheasoft/headas/x86_64-pc-linux 
      $ source $HEADAS/
    2. Then activate their CIAO environment

      $ conda activate ciao
    3. Finally, users have to restore the HEADAS environment variable back to it's original value

      $ export HEADAS=/soft/lheasoft/headas/x86_64-pc-linux 

    Note: this may cause problems using XSpec models in sherpa. Users must not source the script after activating the CIAO environment as it will cause incompatibilities in the suite of parameters tools: pset, pget, and plist.