Astraios vs Siril
Both are free software under the GPL (Astraios GPL-3.0-or-later, Siril GPL-3.0) and cover calibration through stacking and processing. Checked against official Siril sources on : Astraios 0.1.25 (v0.1.25-alpha) and Siril 1.4.4 (released ).
Short version. Siril is the mature, stable, well-documented choice with a large community. Astraios runs its own engine on the GPU, bundles AI denoise and deconvolution, and offers a guided workflow, at alpha maturity. On the same subs with matched settings the two produce the same star peaks and sharpness; see the measured quality comparison. No speed comparison is published yet.
| Astraios 0.1.25 (alpha) | Siril 1.4.4 | |
|---|---|---|
| Price and licence | Free, GPL-3.0-or-later | Free, GPL-3.0 (GitLab) |
| Platforms | Windows, Linux, macOS (Apple Silicon via Metal) | Windows, Linux, macOS with native Apple Silicon and Intel builds (siril.org) |
| Maturity | Alpha, first release 2026, one maintainer | Stable since 2005 (as SIRI-L), 1.4.4 released 2026-06-17, large community and documentation |
| Core-engine GPU acceleration | CUDA and Apple Metal for registration, stacking, deconvolution, denoising, stretching and AI; CPU fallback | None in Siril's own engine: all algorithms are multithreaded on the CPU (siril.org); GPU offload is an open discussion (issue 1450). 1.4.2 improved installing GPU libraries for the Python-script tools it calls (release notes) |
| AI denoise and deconvolution | AI denoise built in with a bundled model; classical and spatially varying deconvolution built in | Not native; reached through scripts that call GraXpert (free) or RC Astro's paid tools (GraXpert interface, RC Astro in Siril) |
| Star removal | Built-in morphological remover; StarNet optional | StarNet via Python script; the legacy built-in interface is deprecated (docs) |
| Calibration, registration, stacking | Built in; verified transforms, winsorized default, drizzle, multi-session | Built in; global star alignment, rejection stacking, drizzle (registration, stacking) |
| Plate solving and colour calibration | Offline local Gaia DR3, ASTAP, astrometry.net; PCC, SPCC, SFCC | Built-in solver with local catalogs; PCC and SPCC with offline Gaia catalogs (PCC, SPCC) |
| Live stacking | Yes | Yes, marked experimental (docs) |
| Planetary lucky imaging | SER stacking, de-rotation, projection | SER support and rejection-based selection; pixel-wise planetary registration (docs) |
| Scripting | Python console, macros, plugins | SSF scripts and Python scripting |
| Guided step-by-step workflow | Yes | No wizard; scripts automate pre-processing |
| Non-destructive history | Yes | Not documented |
| Documentation and support | Docs in the repository, Discussions | Full documentation (readthedocs), community forums |
Working together
Astraios reads Siril's FITS output right side up (it honours ROWORDER), can stack subs Siril registered, and can reuse a Seti Astro Gaia catalog folder. Using Siril for pre-processing and Astraios for the guided post-processing, or the other way round, works.
What Astraios does not have
- Twenty years of stability and a community that has seen every kind of data.
- Siril's photometry and astrometry depth, its scripting ecosystem and its documentation.
- Camera raw support.
Sources: siril.org, Siril 1.4.4 release, Siril 1.4.2 release notes, Siril documentation, Siril issue 1450, Astraios project facts.