Chandra Announcement: CIAO 4.14, DS9 8.3 Released

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Tara Gokas

Dec 14, 2021, 1:49:42 PM12/14/21
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CIAO 4.14, DS9 8.3

The Chandra X-ray Center (CXC) is pleased to announce that version 4.14 of CIAO ("Chandra Interactive Analysis of Observations") is now available for download from .

CIAO 4.14 includes version 8.3 of SAOImage DS9 (the astronomical imaging and data visualization application). DS9 can also be downloaded and installed as a stand-alone application from

CIAO 4.14

Notable change and improvements (read the complete release notes for full details):

  • CIAO can be installed using the conda package manager. Users can install the conda edition of CIAO with Python 3.8 (default), 3.7, or 3.9 on Linux and Mac. The ciao-install script can also be used to install CIAO 4.14 without conda, now with Python 3.8.

  • The prism application has been removed from CIAO. Most of the prism functionality can now be found in ds9 using the  File → Prism option.

  • There are several important tool bug fixes including

  • A new adaptive binning tool, dmradar, implements a polar version of the quad-tree algorithm.

  • CIAO contributed script updates since the previous CIAO release include:

    • Users will notice that on most terminals (and notebooks) that error messages from the scripts are now color coded red. This can be disabled by setting the NO_COLOR environment variable.

    • A new version of specextract that creates the spectrum, ARF, and RMF in parallel, generally providing a factor of 2 or more improvement in performance.

    • A new find_mono_energy script to help compute an appropriate monochromatic energy for a given energy band and spectral model.

    • merge_obs, reproject_obs, and flux_obs now create individual field-of-view (FOV) files along with a merged FOV file.

    • dax uses a new feature in ds9 8.3 to install several common tasks directly into the main ds9 button bar.

  • Sherpa in CIAO 4.14 incorporates changes in standalone versions Sherpa 4.13.1 and Sherpa 4.14.0  - including several important updates:

    • Updated the XSPEC model library to XSPEC version 12.12.0. Note that this requires users of the conda installation to use the conda-forge channel when installing CIAO 4.14.

    • Several improvements to how filtering and grouping are applied to spectral data (1D binned data) include changes to how bin edges are being treated.

    • Important sample_flux modifications including a change to how parameter bounds are treated and  a method to allow users to specify the dataset id.

    • Improvements to how parameter bounds are treated by the optimizer.

    • Continued development of plotting routines.

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

CIAO 4.14 is available for the following platforms (see also the Platform Support Page):

  • Linux 64 bit

    • including CentOS 7 and newer, Ubuntu 18.04 and newer

  • Apple macOS 10.14 (Mojave) through macOS 12 (Monterey).

    • CIAO 4.14 is distributed as Intel/x86 binaries which are compatible with Apple's M1 chip via the Rosetta2 emulation layer.

SAOImage DS9 v8.3

Version 8.3 of SAOImage DS9 includes:

  • The option to display individual color bars for each frame.

  • A new Notepad, File → Notes, where users can record information about their analysis. It can be saved separately and is included in the ds9 backup.

  • Users can now have their Analysis Tasks display buttons on the main ds9 window to provide quick access to commonly used tools.

The existing versions of the Chandra CALDB (version 4.9.6), and MARX (version 5.5.1) remain valid and do not require updating for CIAO 4.14.

As always please send questions and requests for enhancements to the CXC HELPDESK

CIAO, CALDB and DS9 are a collaborative effort between the SAO/CXC Science Data Systems group, the SAO/CXC Data System Division, and MIT/CXC personnel.  MARX is created and maintained by the MIT/CXC/HETG group.

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