Introduction #

We are immensely proud to announce the release of Siril 1.4.0 stable!

After more than two years of intense development that began in 2023, countless hours of work, testing, fixes and improvements, Siril 1.4.0 is finally here. This major version represents the culmination of tremendous work by the entire team and community, and we are thrilled to finally share it with you.

Siril 1.4.0 brings a multitude of major new features, significant performance and stability improvements, as well as a modernized user interface. From the new Drizzle algorithm inherited from the Hubble Space Telescope to astrometric alignment with distortion correction, along with advanced color management and many other innovations, this version profoundly transforms the astronomical image processing experience.

A demanding development cycle #

The development of Siril 1.4.0 has been a marathon rather than a sprint. Started over two years ago, this cycle allowed us to implement complex features that required time, reflection and numerous iterations. The two release candidate versions (RC1 and RC2) published in November 2025 were crucial for identifying and fixing the last issues before this stable release.

We warmly thank all the testers who took the time to try beta and RC versions and provide us with their feedback. Your involvement was instrumental in achieving this level of quality and stability.

What’s new since RC2 #

This stable version integrates the latest fixes identified during the RC2 testing phase:

Improvements #

• Accurate photometry in SirilInterface: the get_selection_star() function now attempts accurate photometry when computing the PSF (!961)

Fixes #

• Fixed get_image_history(): now correctly updates history with operations done since loading
• Fixed RGB composition: compressed FITS files (.fit.fz, .fits.fz) now appear in the file selector (#1878)
• Fixed Gaia online catalogue status indicator (!963)
• Enabled the use of the bad pixel map without having a master dark (#1876)
• Fixed catsearch function for solar system objects (#1882)
• Fixed cleaning python related environment variables within Siril app for Windows (#1880)
• Fixed empty csv file exported by conesearch command when called from script (#1885)

Key features of Siril 1.4.0 #

As a reminder, here is an overview of the major innovations introduced in this version (the complete list is available in the documentation):

Astrometry and calibration #

• Astrometric solving with distortions: full support for SIP convention and blindsolve with Astrometry.net
• Astrometric alignment for mosaics: alignment of images with little overlap
• Distortion correction during alignment: correction of optical aberrations using WCS SIP data
• SPCC (Spectrophotometric Color Calibration): new color calibration method with atmospheric model
• Offline Gaia catalogue support: catalogue extracts with HEALpixel-based indexing

Advanced image processing #

• Drizzle algorithm: implementation of the algorithm used for the Hubble Space Telescope, allowing to increase the effective resolution of images
• Curves Transformation tool: precise control of tonal curves
• Edge-preserving filters: bilateral and guided filters
• Full color management with ICC profiles: fully color-calibrated workflow
• Region of Interest (ROI) processing: application of certain processes to specific areas
• Color Conversion Matrices: for images and sequences

Stacking and mosaics #

• Blending masks and normalization on overlaps: to stitch mosaics with rejection stacking
• Dark scaling: automatic adaptation to exposure time
• Master distortion files: systematic correction of optical aberrations

Scripts and automation #

• Python scripting: complete Python scripting system allowing to extend Siril with your own analysis and processing tools
• Git repository integration: automatic download and update of scripts from Git repositories

Visualization and analysis #

• Internal plotting tool (siril_plot): integrated graphics without dependency on GNUplot
• Intensity profiling: analysis of light distribution
• Local annotation catalogues: IAU constellation lines and names
• New conesearch command: support for new catalogues (VSX, GCVS, exoplanets, AAVSO)

Photometry #

• AAVSO output format: direct export for submission to AAVSO
• Comparison star list creation: from the interface or command line
• Flexible aperture size: automatic adaptation according to FWHM

Interface and ergonomics #

• FITS keyword management: update on images and sequences
• Full mouse configuration: buttons and scroll wheel fully configurable
• JPEG XL format support: import and export

Performance #

• Major optimizations: GHT code refactoring (~2x faster), JSON parsing 10x faster with yyjson
• Better memory management: reduced consumption for sequence operations

Important: macOS support evolution #

Support for macOS < 13 Ventura seriously compromised #

Starting with this version, support for macOS systems prior to version 13 Ventura is seriously compromised, even though it is still technically possible to use Siril on these versions. This is not due to Siril itself but because of the increasing reliance of scripts on third-party software such as Qt6, which have their own schedules for discontinuing support for ancient OS versions, outside our control.

Warning: Many Python scripts are likely to encounter problems on macOS versions below 13. We strongly recommend Mac users to update their operating system to macOS 13 or higher for an optimal experience.

Considering dropping Intel Mac support #

We are also considering, in the more or less near future, dropping support for Intel processors on macOS. Support is expected to continue throughout the 1.4.x stable series but is unlikely to extend to 1.6.x. This decision would allow us to focus our development and optimization efforts on modern architectures. Affected users will of course be informed well in advance if this decision is made.

The book on Siril is coming! #

We are happy to announce that the reference book dedicated to astrophotography and Siril is now printed and will be available in French on December 15, just in time for Christmas! Published by Axilone – Astronomie, this richly illustrated book of approximately 200 pages is the most comprehensive guide ever published on Siril (more info here ).

The English translation has begun and is expected to be available in Q1 2026. Translations in Italian, German, and Spanish are also planned.

What’s next: Siril 1.5 #

Now that Siril 1.4.0 is released, development of Siril 1.5 will begin on the master branch. This new version will bring its share of new features and improvements.

Important note for master branch users: Users accustomed to using daily builds from master are advised to exercise caution during the early phases of version 1.5 development, as this period may be more unstable than usual. We recommend waiting a few weeks after the start of the 1.5 cycle before resuming daily use of the master branch, or use the 1.4 branch to have the small improvements quickly.

Acknowledgments #

This 1.4.0 version would not have been possible without the incredible involvement of the entire development team and its team partners: Cécile Melis, Adrian Knagg-Baugh, Ian Cass, René de Hesselle, Cyril Richard, Vincent Hourdin and all the contributors who participated in the code, documentation, translations and testing. A huge thank you also to our user community who, through their feedback, suggestions and patience, constantly push us to improve Siril.

Thank you all, and happy image processing with Siril 1.4.0!

Report bugs #

If you encounter problems with Siril 1.4.0, please report them via the Siril GitLab site . For bugs encountered with scripts, it’s here .

Your feedback is essential to help us maintain and improve Siril!