jwspecfit 1.1.3

JWST NIRSpec emission-line fitting with resolution-aware Gaussian models

jwspecfit

Emission-line fitting, MCMC, and chemical abundances for JWST NIRSpec spectra.

Three packages, one pipeline — from 1-D NIRSpec spectra to element abundances.

Package	What it does
jwspecfit	Resolution-aware Gaussian line fitting with bootstrap errors
jwspecmcmc ⭐	Bayesian MCMC fitting (NUTS · emcee · nautilus) — recommended
jwspecabund	Chemical abundances — direct T_e · forward model · strong-line

Recommended fitter: for science-quality results the authors recommend the Bayesian MCMC fitter jwspecmcmc (full posteriors and faithful uncertainties). Use the least-squares jwspecfit engine for quick looks, initial guesses, and BIC model selection.

Key features

• Resolution-aware line profiles: bin-averaged Gaussians via erf — correct for prism, gratings, and stacks.
• Broad-Balmer detection: BIC-based selection across four nested models.
• UV doublets: flux-ratio and kinematic tying for C IV, N V, N III], O III], C III], N IV].
• Lyα + DLA: skewed Gaussian + IGM transmission + dynesty N_HI retrieval.
• Dust correction: multi-Balmer A_V anchored on Hβ or Hα, Salim+18 or Cardelli+89 curves.
• Abundances: direct T_e ([O III] 4363 or UV 1666), Cullen+25 forward model, Sanders+25 strong-line.
• ICFs: Martinez+25 (N/O) · Izotov+06 (S, Ne, Ar) · Garnett+97 (C/O).
• Lyα escape fraction with Monte Carlo propagation of A_V uncertainty.

Install

pip install jwspecfit

Or with all optional extras (MCMC backends, abundances, DLA fitter):

pip install "jwspecfit[nuts,mcmc,abund,dla]"

For development (editable install from source):

git clone https://github.com/raunaq-rai/jwspecfit.git
cd jwspecfit
pip install -e ".[dev,nuts,mcmc,abund]"

Requires Python ≥ 3.10. See the installation guide for individual extras.

Example

import jwspecfit, jwspecabund

spec   = jwspecfit.read_fits("spectrum.fits", z=6.0)
result = jwspecfit.fit_lines(spec, z=6.0)
abund  = jwspecabund.compute_abundances(result, z=6.0)

print(abund.summary())

Documentation

Usage guides, API reference, and methodology: https://jwspecfit.readthedocs.io/

Worked examples: docs/notebooks/.

Tests

pytest tests/

Citation

If you use jwspecfit in your research, please cite it. Choose whichever format your reference manager or journal prefers.

📖 DOI: 10.5281/zenodo.19679793

Concept DOI — always resolves to the latest Zenodo-archived release.

Plain text

Rai, R. (2026). jwspecfit: Resolution-aware emission-line fitting, MCMC sampling, and chemical abundances for JWST NIRSpec (v1.0.1). Zenodo. https://doi.org/10.5281/zenodo.19679793

BibTeX

@software{rai_jwspecfit,
  author       = {Rai, Raunaq},
  title        = {{jwspecfit}: Resolution-aware emission-line fitting,
                  MCMC sampling, and chemical abundances for JWST NIRSpec},
  year         = {2026},
  version      = {1.0.1},
  publisher    = {Zenodo},
  doi          = {10.5281/zenodo.19679793},
  url          = {https://doi.org/10.5281/zenodo.19679793},
}

Other formats

APA · Chicago · IEEE · Harvard · MLA · CSL-JSON · DataCite XML are all available from the Zenodo record page (Export panel on the right).

GitHub's "Cite this repository" button (top-right of the repo page) reads CITATION.cff and produces APA/BibTeX on the fly.

Pinning a specific version

The concept DOI above always points to the latest release. If a paper needs to cite the exact code version used for reproducibility, pick the per-version DOI from the "Versions" list on the Zenodo page.

Licence

MIT — see LICENCE.