speclib

Tools for working with stellar spectral libraries.

speclib provides a lightweight Python interface for loading, manipulating, and analyzing stellar spectra and model grids. It includes utilities for photometric synthesis, spectral resampling, and SED construction using libraries such as PHOENIX.

---

Installation

With Poetry (recommended):

git clone https://github.com/brackham/speclib.git
cd speclib
poetry install

Or with pip:

pip install git+https://github.com/brackham/speclib.git

---

Requirements

• Python 3.11 to 3.13
• astropy
• specutils
• synphot

---

Example

from speclib import Spectrum, Filter, apply_filter

spec = Spectrum.from_grid(teff=4000, logg=4.5, feh=0.0)
filt = Filter("2MASS J")
flux = apply_filter(spec, filt)

print(f"J-band flux: {flux:.2e}")

Custom library cache location

Downloaded spectral libraries are stored in ~/.speclib/libraries by default. Set the SPECLIB_LIBRARY_PATH environment variable or call speclib.utils.set_library_root("/path/to/cache") to use a different location.

NewEra grid caching and extraction

NewEra grid downloads now keep the tarball cached without unpacking by default. When a specific metallicity file is needed, it is extracted on demand from the cached archive. To explicitly extract the full grid (for offline usage or bulk access), use the extract="all" option:

from speclib.utils import download_newera_grid

# Cache the tarball only (default behavior)
download_newera_grid("newera_jwst")

# Extract all members from the tarball
download_newera_grid("newera_jwst", extract="all")

---

License

MIT © 2025 Benjamin V. Rackham