wcc-sim: Image Simulator for the Lazuli WCC
wcc-sim makes synthetic images of what the Wide-field Context Camera (WCC) on Lazuli would see. You give it a pointing on the sky. It looks up the real stars there in Gaia DR3, works out how many electrons each one produces in the detector, draws every star with the camera’s point-spread function, adds the noise a real exposure would have, and writes a FITS image you can analyse like data.
The instrument numbers (throughput, detector noise, saturation) come from the
wcc-etc exposure time
calculator, so an image from wcc-sim and a signal-to-noise estimate from the
ETC agree by construction. The companion package wcc_phot measures
differential photometry on a series of those images.
In more detail: the Gaia photometry of each star is converted to a detector
count rate through the wcc-etc instrument model; the star is rendered with the
in-focus (Airy) or +1/+2-wave defocus (Zemax Huygens) PSF; photon, sky, dark
and read noise are added with full-well and ADC saturation; and the result is
written as a multi-extension FITS file (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. Terms such as ADU, full well, n_reads or
TAN WCS are defined in the Glossary.
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_etcexposure 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) andqcmos:*(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
CLEANimage for photometric closure tests.Plots built in.
field.plot(),field.plot_cutout(),field.plot_psf_profile()and theresult.plot_*methods ofwcc_photdraw the standard views with one call, each takingax=(see Plotting).
Contents
Getting started
User guide
Tutorials