Getting Started with GLEE

GLEE (Gravitational Lens Efficient Explorer) is a software package for modelling strong gravitational lens systems. It supports a wide variety of lensing analyses:

• Point-source modelling — fitting quasar or supernova image positions in the source or image plane.
• Extended-source modelling — reconstructing the full surface brightness distribution of lensed arcs.
• Time-delay cosmography — constraining the Hubble constant $H_0$ from lensed quasar time delays.
• Multiplane lensing — modelling systems with multiple lens planes at different redshifts.

GLaD (Gravitational Lensing and Dynamics) extends GLEE with stellar-dynamical constraints, enabling joint lensing+dynamics analyses.

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How to Use This Wiki

The wiki is divided into three main sections:

Section	What you'll find
💡 How to GLEE	Config file reference, the glee.py wrapper, and step-by-step tutorials
⚖️ Mass Profiles	Mathematical definitions and GLEE config usage for all mass models
🌟 Light Profiles	Mathematical definitions and GLEE config usage for all light models

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Recommended Learning Path

If you're brand new to GLEE, follow this path:

1. Tutorial 0 — Preliminary Data: Learn what files you need to prepare (cutout, masks, PSF, error map).
2. GLEE Configfile: Understand the structure of the config file that drives every GLEE run.
3. Tutorial 1 — Source Plane Positions: Run your first lens model optimisation.
4. Tutorial 2 — Image Plane Positions: Refine the model in the image plane for more robust results.
5. Tutorial 3 — Surface Brightness: Fit the full extended arc and lens light.

Once you are comfortable with the basics, explore the Mass Profiles and Light Profiles sections for detailed parameter descriptions of each model.

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Quick Reference

Running GLEE

# Optimise (simulated annealing)
glee.py minimise -o output_config input_config

# Compute χ²
glee.py chi2 input_config

# Run MCMC
glee.py mcmc input_config

# Predict image positions
glee.py predict input_config

Typical Workflow

Prepare data (Tutorial 0)
       ↓
Source-plane optimisation (Tutorial 1)
       ↓
Image-plane optimisation (Tutorial 2)
       ↓
Surface brightness modelling (Tutorial 3)
       ↓
MCMC sampling → posterior analysis

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Citations

If you use GLEE or GLaD in your research, please cite:

@article{Suyu2010,
  author  = {Suyu, S. H. and Halkola, A.},
  title   = {The halos of satellite galaxies: the companion of the massive elliptical lens SL2S-J08544-0121},
  journal = {Astronomy and Astrophysics},
  year    = {2010},
  volume  = {524},
  pages   = {A94},
  doi     = {10.1051/0004-6361/201015481}
}

@article{Suyu2012,
  author  = {Suyu, S. H. and others},
  title   = {Disentangling Baryons and Dark Matter in the Spiral Gravitational Lens B1933+503},
  journal = {The Astrophysical Journal},
  year    = {2012},
  volume  = {750},
  pages   = {10},
  doi     = {10.1088/0004-637X/750/1/10}
}