BLiSS — Blind Line Search System

BLiSS (Blind Line Search System) is an open-source Python package for the automatic detection and identification of emission lines in astronomical spectra.

Rather than requiring users to manually inspect spectra or provide a list of candidate line energies, BLiSS performs a genuine blind line search directly on the data, ranking statistically significant emission-line candidates and optionally identifying them using atomic databases.

Originally developed for X-ray spectroscopy, BLiSS is designed around a general workflow that can be applied to any spectral dataset with associated uncertainties.

Features

• Blind emission-line search

  • Automatically searches spectra for statistically significant emission features.
  • No prior knowledge of line positions is required.

• Automatic Gaussian fitting

  • Fits candidate features with Gaussian profiles.
  • Provides statistical ranking of all detected lines.

• Continuum-independent workflow

  • Line searches can be performed without defining a global continuum model beforehand.

• Atomic line identification

  • Cross-matches detected features with XSTAR atomic transitions.
  • Supports Doppler velocity constraints.

• Flexible rebinning

  • Rebin spectra by instrumental resolution or target signal-to-noise ratio.

• Null-spectrum evaluation

  • Reports five global Monte Carlo p-values based on synthetic null spectra.
  • Provides an additional empirical BLiSS score derived using Gaussian mixture modelling.

• Reproducible analyses

  • Applies identical search criteria across large spectral samples.

Installation

Install BLiSS directly from PyPI:

pip install bliss-lib

or install the development version from GitHub:

git clone https://github.com/xragua/bliss.git
cd bliss
pip install -e .

Quick start

import bliss

# Import your spectrum

# Run the blind line search

# Inspect the detected candidates

Example notebooks are available in the notebooks/ directory:

https://github.com/xragua/BLiSS/tree/main/notebooks

Documentation

GitHub repository:

https://github.com/xragua/bliss

Latest releases:

https://github.com/xragua/bliss/releases

Requirements

• Python 3.10 or newer
• NumPy
• SciPy
• Pandas
• Astropy
• Matplotlib

These dependencies are installed automatically with BLiSS.

Citation

If you use BLiSS in your research, please cite:

@misc{abalo2026blindlinesearchsystem, title={Blind Line Search System: BLiSS}, author={Luis Abalo and Graciela Sanjurjo-Ferrín and Jessica Planelles-Villalva and José Joaquín Rodes-Roca and José Miguel Torrejón}, year={2026}, eprint={2607.07783}, archivePrefix={arXiv}, primaryClass={astro-ph.IM}, url={https://arxiv.org/abs/2607.07783}, }

Support

Bug reports, feature requests and suggestions are welcome through GitHub Issues:

https://github.com/xragua/bliss/issues

License

This project is distributed under the MIT License.