Chandra Announcement: CIAO 4.15, DS9 8.4, MARX 5.5.2 released

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Tara Gokas

Dec 13, 2022, 2:57:35 PM12/13/22
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CIAO 4.15, DS9 8.4, MARX 5.5.2 released 

The Chandra X-ray Center (CXC) is pleased to announce that version 4.15 of CIAO ("Chandra Interactive Analysis of Observations") is now available for download from

CIAO 4.15 includes version 8.4 of SAOImage DS9 (the astronomical imaging and data visualization application). DS9 can also be downloaded and installed as a stand-alone application from

Version 5.5.2 of MARX (the Chandra on-orbit performance simulator) can be installed as part of the CIAO installation or separately from

CIAO 4.15 and contributed scripts

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 3.10, 3.9, or 3.8 on Linux and Mac. The ciao-install script can also be used to install CIAO 4.15 without conda, now with Python 3.9.

  • wavdetect updates to improve robustness of detecting low significance sources and to remove artificial duplicate sources.

  • tg_resolve_events now properly resolves HRC events in the HEG/MEG overlapping region.

  • dmimgcalc can now be used to specify an arbitrarily long expression by using stacks.

  • Improved uniformity including scripts adding HISTORY records, images recognizing NULL values, and copying world coordinate systems (WCS) from images to tables.

  • Sherpa in CIAO 4.15 incorporates changes in standalone versions Sherpa 4.14.1 and Sherpa 4.15.0  - including 

    • Updated to version 12.12.1c of the XSPEC model library.

    • Updates in  the chi2xspecvar statistics

    • Models can now be frozen or thawed when accessing the model objects directly.

    • Updates in filtering and grouping

    • Plotting improvements

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

The latest release of the contributed CIAO scripts includes several new scripts and important updates, including

  • psf_contour (new) creates source regions based on simulated PSFs.

  • bkg_fixed_counts (new) creates background regions which enclosed a specified number of counts.

  • aplimits (new) computes upper limits for false detection and missed detections.

  • statmap (new) computes a simple statistic (min, max, mean, median, etc) of a column in an input table based on the input map file (eg as output from dmnautilus or dmradar).

  • specextract now, by default, uses the center of the extraction region when computing PSF fractions and unweighted ARFs. The new resp_pos parameter allows users to select different algorithms to determine the response position, including the previous MAX algorithm (location of pixel with maximum value).

  • srcflux supports user plugins to perform custom analysis.

  • dax added an interactive tool to compute grating coordinates.

For more details and a complete list see the Analysis Scripts release notes.

CIAO 4.15 is available for the following platforms (see also the Platform Support Page):

  • 64-bit Linux distributions, CentOS7 / Ubuntu 18.04 era and newer

  • macOS Intel x86 and Apple ARM (M1/M2, using Rosetta2 emulation), Catalina (10.15) through Ventura (13).

SAOImage DS9 v8.4

Version 8.4 of SAOImage DS9 includes:

  • New layout views: Basic and Advanced

  • New Illustration: users can add graphics for presentations

  • Fade between images, save as GIF movies

  • Improvements in access to regions' analysis results via XPA and SAMP.

For a complete list of changes see the SAOImageDS9 version 8.4 Release Notes page.

MARX 5.5.2

The MARX 5.5.2 release ( upgrades the calibration data used by MARX to CalDB 4.10.2 

MARX 5.5.2 is the version that should be used for cycle 25 proposal preparation. 

See the MARX changelog for further details on this release.

The existing version of the Chandra CALDB (version 4.10.2) remains valid and does not require updating for CIAO 4.15

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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