wcc-sim: Image Simulator for the Lazuli WCC

wcc-sim is the end-to-end photometric image simulator for the Wide-field Context Camera (WCC) on Lazuli. Given a pointing (RA, Dec) it queries Gaia DR3, converts each star’s Gaia photometry to detector count rates through the wcc-etc instrument model, renders every star with the in-focus (Airy) or +1/+2-wave defocus (Zemax Huygens) PSF, adds photon/sky/dark/read noise with full-well + ADC saturation, and writes a multi-extension FITS image (SCI + SATMASK + CAT + CLEAN) with a TAN WCS.

Note

New here? Read Installation and then work through Quick start. The Tutorials are runnable Jupyter notebooks that cover every major feature end to end, and Command-line interface documents the wcc-sim command line.

Highlights

• One call, one image — simulate_field() goes from (RA, Dec) to a calibratable FITS image in ~11 s for the full 9568×6380 px Sony IMX455 array.

• Real sky — Gaia DR3 cone search with an on-disk cache; each star’s BP−RP color is mapped to a Pickles spectral type and normalized to its G magnitude before integration through the instrument throughput.

• Faithful instrument model — count rates, sky background, dark current, read noise, full-well and ADC saturation all come from the wcc_etc exposure time calculator, so the simulator and the ETC agree by construction.

• Three PSF modes — in-focus Airy, +1-wave and +2-wave defocus (Zemax Huygens data), rendered on an oversampled grid with sub-pixel placement and optional Gaussian jitter blur.

• Two detectors — zwo:* (Sony IMX455, 9568×6380 px, 16.87 mas/px) and qcmos:* (Hamamatsu HWK4123, 4096×2304 px, 20.64 mas/px).

• Analysis-ready output — multi-extension FITS with a TAN WCS, per-pixel saturation mask, the injected Gaia catalog (with pixel positions, spectral types, rates, and saturation flags), and an optional noiseless CLEAN image for photometric closure tests.

Contents

Getting started

• Installation
  • Requirements
  • Install from source
  • Using a conda environment
  • Verify the installation
  • Running the test suite
  • Building the documentation locally
• Quick start
  • The mental model
  • 1. Simulate a field
  • 2. Inspect the result
  • 3. Or use the command line
  • 4. Read the FITS output back
  • Where to go next

User guide

• User guide
  • Concepts: the pipeline
  • Gaia catalogs
  • From Gaia photometry to count rates
  • PSFs and defocus
  • Noise and saturation
  • FITS output and WCS

Tutorials

• Tutorials

Reference

• Command-line interface
  • Options
  • Cookbook
  • Example scripts
• API reference
  • Top-level public API
  • Modules
• Changelog
  • 0.1.0 (2026-07-02)

Indices and tables

• Index

• Module Index

• Search Page