ExoSim 2

Introduction

ExoSim 2 is the next generation of the Exoplanet Observation Simulator ExoSim tailored for spectro-photometric observations of transiting exoplanets from space, ground, and sub-orbital platforms. This software is a complete rewrite implemented in Python 3, embracing object-oriented design principles, which allow users to replace each component with their functions when required.

Table of contents

• ExoSim 2
  • Introduction
  • Table of contents
  • How to install
    • Install from PyPI
    • Install from source code
      • Test your installation
  • Documentation
    • Build the html documentation
    • Build the pdf documentation
  • Agentic support for AI assistants
  • How to contribute
  • How to cite

How to install

Install from PyPI

ExoSim 2 is available on PyPI and can be installed via pip as

pip install exosim

Install from source code

ExoSim 2 is compatible (tested) with Python 3.12 and 3.13

To install from source, clone the repository and move inside the directory.

Then use pip as

pip install .

Test your installation

If you have installed ExoSim from source code, to test your ExoSim 2 installation simply run from the main ExoSim 2 folder:

uv sync --dev
uv run pytest tests

Documentation

ExoSim2 comes with an extensive documentation, which can be built using Sphinx. The documentation includes a tutorial, a user guide and a reference guide.

To build the documentation, install the needed packages first via uv:

uv sync --extra dev,docs

Build the html documentation

To build the html documentation, move into the docs directory and run

make html

The documentation will be produced into the build/html directory inside docs. Open index.html to read the documentation.

Build the pdf documentation

To build the pdf, move into the docs directory and run

make latexpdf

The documentation will be produced into the build/latex directory inside docs. Open exosim2.pdf to read the documentation.

Here is reported the use of pdflatex, if have another compiler for LaTex, please refer to sphinx documentation.

Agentic support for AI assistants

ExoSim 2 includes repository-local guidance for LLM and coding-agent tools. These files help assistants answer questions, choose the correct pipeline, and set up parameters from local evidence instead of guessing scientific defaults.

The support includes:

• AGENTS.md: canonical shared guide for OpenCode, Warp and generic repository-aware agents.
• CLAUDE.md: Claude Code entry point.
• WARP.md: Warp compatibility entry point.
• .github/copilot-instructions.md and .github/instructions/: GitHub Copilot repository and path-specific instructions.
• docs/ai-agents/codebase-map.md: source, documentation, examples and validation map.
• docs/ai-agents/parameter-setup-guide.md: XML/YAML parameter setup workflow, including __ConfigPath__, <config> includes and unit handling.
• docs/ai-agents/agent-playbooks.md: reusable roles for parameter setup, pipeline selection, scientific review and developer maintenance.

The rendered documentation page is docs/source/agentic_support.rst.

How to contribute

You can contribute to ExoSim 2 by reporting bugs, suggesting new features, or contributing to the code itself. If you want to contribute to the code, please follow the steps described in the documentation under Developer guide/Contributing guidelines.

How to cite

If you use ExoSim 2 in your research, please cite the following paper:

Mugnai, L.V., Bocchieri, A., Pascale, E. et al. ExoSim 2: the new exoplanet observation simulator applied to the Ariel space mission. Exp Astron 59, 9 (2025).