BXA

At a glance

• Editor score
  5.8 / 10
• Pricing
  Open source
• Best for
  Bayesian astronomical model fitting
• Paid from
  Free
• Facts checked
  23 Sep 2026

• Where it wins

  • Bayesian estimation, evidence calculation and model comparison in one workflow
  • MPI parallelization and automated nested-sampling convergence tools
  • Integrates with XSPEC, Sherpa and UltraNest, with diagnostic plots

• Where it doesn't

  • Linux-focused, self-hosted deployment limits platform flexibility
  • Specialized for X-ray spectral analysis rather than broad astronomy workflows
  • Requires compatible XSPEC or Sherpa environments and research-oriented setup

Our verdict on BXA

BXA is an open-source Python package for researchers performing Bayesian X-ray spectral analysis. It connects the XSPEC and Sherpa environments with UltraNest, supporting individual spectra and large collections of X-ray datasets. The package is aimed at solo researchers and small or mid-market research teams working in a Linux, self-hosted environment rather than people seeking a consumer sky-viewing application.

Its strongest case is the depth of its statistical workflow. BXA provides Bayesian parameter estimation in arbitrary dimensions, best-fit and error-bar calculations, marginal probabilities, and posterior-sample visualizations. Model evidence supports Bayes-factor calculations, while model comparison goes beyond nested likelihood-ratio tests. Quantile-quantile plots support model discovery, spectral model-versus-data plots aid interpretation, and automated nested-sampling convergence helps monitor inference. MPI parallelization is available for workloads that benefit from distributed computation.

Integration is central to the product’s fit. Existing XSPEC or Sherpa workflows can connect to UltraNest through BXA, keeping established X-ray analysis environments in the loop while adding Bayesian sampling and comparison capabilities. Installation is available through pip or conda on operating systems supported by Sherpa or XSPEC, with Linux listed as the platform and self-hosting as the deployment model. Documentation and community channels provide the support path. Choose BXA when your work centers on reproducible Bayesian modeling of X-ray spectra and you can manage a research-oriented Python environment. A general astronomy audience, or a team seeking a managed multi-platform application, should look elsewhere.

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BXA pricing

BXA fact sheet

BXA integrations

BXA lists 3 integrations on its own site.

• XSPEC
• Sherpa
• UltraNest

Alternatives to BXA

• SStellariumA capable free desktop planetarium with telescope control, scripting, and offline access.9.3
• KStarsA capable free desktop toolkit for sky simulation, planning, and astrophotography.9.2
• WorldWide TelescopeA free, open-source astronomy platform for visualization, tours, and telescope projects.9.1

See all BXA alternatives →

Featured on iTechGuides

BXA is listed in our Astronomy Apps directory. Add the badge to your site — it links back to this page.

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

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Last updated 7 Oct 2026 · How we research and update