# `photometry`
## Scientific scope
`siderust::photometry` owns astronomical photometric concepts: photometric
systems, spectral response curves (passbands), throughput unit, synthetic
photometry, and color indices. Generic sampled-spectrum infrastructure lives
in `optica::spectrum`.
## Technical scope
What you will find here:
- `passbands/`: curated built-in filter datasets such as Bessell 1990 UBVRI,
with lazily-initialised, statically-cached `SampledSpectrum<Nanometer, Throughput>`
constants and `johnson_b()` / `johnson_v()` convenience accessors.
- `mod.rs`: thin re-export of [`Throughput`].
Use `optica::spectrum::{SampledSpectrum, Interpolation, SpectrumError}` and
`optica::spectrum::loaders` for generic spectrum handling.