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Last modified: 1 March 2024


CIAO 4.14 Release Notes

CIAO 4.14 is distributed for the following platforms:

Visit our platform support page for our statement about support for Apple's M1 (ARM) chip support used with macOS 11 (Big Sur) and 12 (Monterey). .

CIAO is available using the conda package manager: conda builds are available for Linux and Mac for Python 3.9, 3.8, and 3.7. More information can be found in the conda section of the Installation notes below.

There is no support for 32 bit operating systems, older Linux (CentOS 6 era) or older macOS platforms (macOSX High Sierra and earlier). More details can be found on the Platform Support page.

Notable changes and improvements in CIAO 4.14

  • CIAO 4.14 includes several important bug fixes and includes updates to support newer compilers. There have been enhancements to sherpa and CIAO 4.14 also provides updates to Off The Shelf (OTS) packages like SAOImage DS9.

  • CIAO can be installed using the conda package manager. Users can install the conda edition with Python 3.9, 3.8, or 3.7 on Linux and Mac.

    CIAO 4.14 conda install requires conda-forge channel

    Updating to the latest version of XSpec requires CIAO to use a newer version of libgfortran, which is not available in the default channel.

    Therefore users will need to include the conda-forge channel when they install CIAO 4.14. Because of this, users are encouraged to create a new conda environment for CIAO 4.14 rather than trying to upgrade an existing environment.

    $ conda create -n ciao-4.14 -c -c conda-forge \
    ciao sherpa ds9 marx ciao-contrib caldb_main

    The default version of Python is variable and will depend on which other packages are available at the time of installation. Users who want a specific version of python must include python=3.7, python=3.8, or python=3.9 on the conda create command.

    Alternatively, the ciao-install script can be used to install CIAO 4.14 without conda, now with Python 3.8.

  • Several tools have been updated including important bug fixes:

    • The ardlib default bad pixel mask, BPMASK, now includes the recently added Frame Store Shadow bits. This fixes the problem where the Effective Area is erroneously higher at the bottom edges of the CCDs. For details see the Caveats about ACIS Frame Store Shadow Bad Pixels page. This affects the following tools: mkarf, mkgarf, mkwarf, mkinstmap, and dither_region.
    • The azimuth angle, phi, used to determine the vignetting factor to the effective area has been corrected. Depending on energy and off-axis angle, this could lead an error of up to several percent when using mkarf, mkgarf, and mkinstmap. It does not affect mkwarf. For additional details see the Caveats about Vignetting sign error bug page.
    • The dmextract bug has been fixed which caused it to use the last GTI rather than the first when computing light curves. This is only a significant issue if the per-chip GTIs are significantly different.
    • [New]dmradar is an adaptive binning tool using a quad-tree algorithm similar to dmnautilus but in polar coordinates.
    • dmdiff has been through a major overhaul to provide more robust comparisons -- especially with arrays and WCS parameters.
  • Notable Sherpa changes include:

    • Update to XSPEC 12.12.0 which includes new models: xsgrbjet, xswdem, xsvwdem, xsvvwdem and xszxipab , and updates to parameter limits. New abundance tables, lpgp and lpgs, from Lodders et al.(2009) are now included. ETABLE model files can now be ready with load_xstable_model by setting the etable parameter. The default XSPEC chatter level has been increased from 0 to 10.
    • Filtering and grouping area for binned (1D) spectral data has been improved with changes to the default behavior and many bug fixes resulting in changes to the statistics, degrees-of-freedom and energy flux in comparison to the previous version for the same data with the same filter.
    • Update to sample_flux flux calculations including using the dataset id rather than using the default dataset, returning the statistic value for each iteration (even if rows are not used in flux distribution), corrections to the "clip" array, and it no longer excludes samples at the parameter soft bounds when calculating the flux distribution.
    • Continued plotting improvements and optimization updates.

    As a reminder, Sherpa is also available as a stand alone system, accessible from the Sherpa GitHub repository or from the standalone Sherpa page.

  • The CXC Datamodel has several updates mostly focuses on providing better support for scaled integer images, and in particular, the treatment of NULL valued pixels (ie the FITS BLANK keyword).

  • There have been several script updates since the CIAO 4.14 release including:

    • specextract has been upgraded to support parallel processing, generally providing a factor of 2 or more improvement in runtime performance.
    • [New] The find_mono_energy script can be used to compute an appropriate monochromatic energy for an energy band given an ARF and RMF and a spectral model.
    • merge_obs, reproject_obs, and flux_obs now create individual field-of-view (FOV) files along with a merged FOV file.
    • dax now installs several common tasks into the new ds9 analysis button bar.
  • CIAO includes version 8.3 of SAOImage ds9. Users are reminded that they now need to change the Edit mode setting in order to select or create regions in recent versions of ds9. Please see the watchout page for more information on this.

    SAOImageDS9 v8.3 highlights include:

    • Option to display individual color bars for each frame.
    • New note pad which can be saved separately and is included in backup
    • Support for User defined Analysis buttons

    ds9 image showing mult frams

    Also, the CIAO ds9 wrapper script now preserves the users' LD_LIBRARY_PATH when it runs the ds9 executable.

  • The prism application has been removed from CIAO. Most of the prism functionality has been implemented in ds9. To launch prism from the command line :

    $ ds9 -prism filename

    or use the menu File → Prism option.

How CALDB 4.10.2 Affects Your Analysis

CALDB 4.10.2 Release Notes (release 15 November 2022)

ACIS Imaging and Grating Data

How CALDB 4.9.8 Affects Your Analysis

CALDB 4.9.8 Release Notes (release 15 June 2022)

HRC Data

How CALDB 4.9.7 Affects Your Analysis

CALDB 4.9.7 Release Notes (release 24 March 2022)

ACIS Imaging and Grating Data

How CALDB 4.9.6 Affects Your Analysis

CALDB 4.9.6 Release Notes (release 21 September 2021)


CALDB 4.9.6 is the latest CALDB release. There are no CALDB updates being released concurrently with CIAO 4.14.

ACIS Imaging and Grating Data

HRC Data


Users should be aware of these installation items before installing CIAO 4.14. Additional problems which are seen less frequently are listed on the Installation & Smoke Tests bug page.

Supported Platforms

Installing with the conda package manager

Updates to the ciao-install Installation Script

Source builds

Smoke Tests

IPython Settings

Remove old parameter files





























Parameter Files

This section provides a summary of the changes to parameter files in this release. Refer to the Tools and Analysis Scripts sections of these release notes for complete details.

We recommend deleting all the old parameter files or renaming the parameter-file directory before running any new version of CIAO to avoid conflicts. More information is available in the FAQ.





Sherpa is developed as a community project, and is available on GitHub. Comments, fixes, and additions from the community are welcomed. There are additional releases for this version throughout the year, and can be installed either directly from GitHub or using the conda package manager, as described on the standalone Sherpa documentation page.


Graphical User Interfaces

The prism application has been removed from CIAO. Most of the prism functionality has been implemented in ds9. To launch prism from the command line:

$ ds9 -prism filename

or using the menu File → Prism option.

Analysis Scripts

There have been several updates to the contributed scripts package since CIAO 4.13 was released. These changes are specific to the CIAO 4.14.0 contributed scripts release.

Colorized Errors

















Python Modules










Off-the-Shelf (OTS) Package Versions

Compiler versions


Many pages have been updated to reflect the changes in this release. Several analysis threads are still under review.