MOSFiT

Welcome to the documentation for MOSFiT 2.0 (The Modular Open Source Fitter for Transients), a Python 3.11+ package for fitting and estimating the parameters of astronomical transients via user-contributed models. Development installs use uv; the default sampler is nested sampling with dynesty.

Please see the links below for information on how to install and run the package.

Using MOSFiT

• Installation
  • Installing from source
  • Installing with pip
  • Setting up MOSFiT with Anaconda
  • Lightweight install for rest-frame SEDs
  • Docker
• Getting started
  • Parallel execution
  • Using your own data
  • Producing outputs
  • Visualizing outputs
  • Outputs and provenance
  • Troubleshooting
• Models
  • List of built-in models
  • Altering an existing model
  • Creating a new model
• Fitting data
  • Event data
  • ASCII / catalog JSON
  • Sampling Options
  • Input and output locations
  • Fixing model parameters
  • Initializing from previous runs
• Outputs
  • Light curve options
  • Mock light curves in a magnitude-limited survey
  • Saving the chain
  • Arbitrary outputs
  • Rest-frame SEDs for external light-curve simulators
• Using as a package
  • Produce model outputs
  • Fitting in Python
• Assessing models
  • Convergence
  • Scoring
• Model errors
  • Maximum likelihood analysis
• Accessibility
• Help
  • Frequently Asked Questions
  • Contact
• Command line arguments
  • mosfit
• API
  • mosfit.modules Package

Release notes are in CHANGELOG.md at the repository root (Keep a Changelog: stage work under Unreleased, then move it under a version heading when a tag is cut).

Indices and tables

• Index

• Module Index

• Search Page

License & Attribution

Copyright 2016-2026, James Guillochon, Matt Nicholl, and contributors.

The source code is made available under the terms of the MIT license.