Chandra Announcement: CIAO 4.18, Sherpa 4.18, CALDB 4.12.3, SAOImageDS9 8.7b2, and MARX 6.0.1 Released
Tara Gokas
CIAO 4.18, Sherpa 4.18, CALDB 4.12.3, SAOImageDS9 8.7b2, and MARX 6.0.1 Released
The Chandra X-ray Center (CXC) is pleased to announce the release of the following new software packages:
CIAO 4.18 (Chandra Interactive Analysis of Observations)
Sherpa 4.18 (CIAO Modeling and Fitting Application)
CALDB 4.12.3 (Chandra Calibration Database)
SAOImageDS9 v8.7b2 (Astronomical Imaging and Visualization Application)
MARX 6.0.1 (Chandra On-Orbit Performance Simulator)
These are available to download on the CIAO, CALDB, Sherpa, DS9, and MARX Download Page
They are also available individually at:
Sherpa: Sherpa Standalone Page
SAOImageDS9: DS9 Standalone Page
MARX: MARX Standalone Page
CIAO 4.18 HIGHLIGHTS
Platform Support:
macOS 13 (Ventura) through macOS 26 (Tahoe) for Intel/x86 and ARM (Apple Silicon).
Linux 64-bit (built on RedHat Enterprise 8; tested on Ubuntu 24.04 LTS).
More information is available on the Platform Support Page.
Notable Updates:
Expanded FITS Support: Many CIAO tools (including dmcopy, dmlist, dmstat, dmsort, dmextract, and others) now support the FITS K-type, 8 byte integer, aka "long long", data type. This is needed to correctly read, filter and process modern FITS files that contain large or high-precision integer values.
Installation: Available via conda, the updated ciao-install script or, on macOS via a DMG installer that places CIAO in the /Applications folder.
Python 3.12 Support: CIAO 4.18 ships with Python 3.12.
SAOImageDS9: Version 8.7b2 is included with CIAO 4.18. Users of Ubuntu 25.10 need to manually install the Ubuntu 25.10 build of SAOImageDS9 8.7b3.
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Key Bug Fixes:
acis_process_events now correctly applies the temperature-dependent CTI correction for a small subset of events (primarily in CC-mode) that were previously handled incorrectly.
glvary includes an important bug fix for cases where internal event filtering occurs (e.g., significantly different GTIs between chips)
CONTRIBUTED SCRIPTS UPDATES
The acis_split_evt_by_fptemp script automates the steps outlined in the Extracting Spectra and Responses for ACIS Observations that Undergo Large Focal-plane Temperature Swings thread.
dax has several new Interactive Region analysis tasks. When each of these tasks is enabled for the selected regions, different analysis tasks will be run as the region is moved/edited. This includes: getting total counts, plotting light curves and spectra, and elastic ellipse which will reposition, reorient, and resize the region to match the 2nd order image moments of the data in the region.
sherpa_contrib.stats.kaastra17 module implements the approximation from Kaastra 2017 to identify whether the best-fit model found with the CStat statistic is a good description of the data.
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Read the Analysis Scripts release notes for full details.
SHERPA UPDATES
Sherpa in CIAO 4.18 incorporates changes and bug fixes in standalone versions Sherpa 4.17.1 and 4.18.0 including:
New Optimizers: Support for optimization methods from SciPy and optimagic.
New Statistic: Addition of the cstatnegativepenalty statistic to improve behavior when the parameter search space includes regions which produces negative model values.
Improved Plotting: Ability to plot multiple datasets with a single command (e.g., plot_data, plot_fit_resid) and to apply per-dataset plot attributes.
Bayesian Workflow Enhancements: A streamlined method to convert MCMC-based low-count spectral results (from pyblocxs) for use with the ArviZ package for Bayesian model exploration.
Jupyter Notebook Support: Users working in notebooks are encouraged to try the notebook_plotter tool for interactive model visualization and fitting.
More details can be found on the Sherpa Latest Updates page.
Sherpa is also available as a standalone system from the Sherpa GitHub repository or the standalone Sherpa page.
CALDB 4.12.3
Chandra Calibration Database (CALDB) 4.12.3 includes:
ACIS QE CONTAM version N0016
HRC-I QE file set version N0017 (43 new files). Includes three additional files, and replaces the previous N0016 file set. The final file in the set is effective 2025-02-23.
Proposal Cycle 28 PIMMS Effective Areas: For proposal planning only; not for use in CIAO.
To understand if this CALDB upgrade affects your current analysis, check: "How CALDB 4.12.3 Affects Your Analysis."
SAOImageDS9
SAOImageDS9 version 8.7b2 is included with CIAO 4.18. Version 8.7b3 is available as a standalone application. Key features include:
Autosave: DS9 will now periodically create backup files that can be restored if the application exits unexpectedly. Users can disable or change the backup cadence in the preferences.
Improved SAMP hub: error checking and performance especially on multi-user systems.
Cloud Computing documentation: added instructions on how to set up remote analysis tasks.
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Users of a Linux OS with a new version of libxml2 (2.14.0 or later) need to update the DS9 provided in CIAO 4.18 to version 8.7b3 or later.
For a complete list of changes see the SAOImageDS9 version 8.7 beta release notes.
MARX 6.0.1
MARX 6.0.1 adds a minor bugfix on top of the major MARX 6.0.0 release, which removed obsolete code and made user warnings and errors more useful. Note that there are some changes that are not backward compatible:
The “Verbose” parameter in marx.par files is now an integer, for finer control of the level of output.
The tools marx2img, marx2dpe, and similar tools have been removed. Instead, users should run marx2fits and then CIAO tools to convert to images or other formats.
IDL scripts for reducing MARX spectra have been removed. Use CIAO tools for spectral analysis instead.
In addition, MARX now provides clearer errors and warnings for common input problems, such as setting source coordinates far outside of the field of view, and includes clean-up of internal code by removing experimental configurations, obsolete modules, and support for 32-bit architectures.
As always, please send questions and requests for enhancements to the CXC Helpdesk.
CIAO, CALDB, and SAOImageDS9 are a collaborative effort between the SAO/CXC Science Data Systems group, the SAO/CXC Data System Division, and MIT/CXC personnel. MARX is developed and maintained by the MIT/CXC/HETG group.