What's new?

Version 0.9 adds two pure-Python extraction backends, so PyReduce can run without a compiled C extension, and replaces PYREDUCE_USE_CHARSLIT with PYREDUCE_EXTRACTION (c, charslit, numba, numpy). See CHANGELOG.md for all changes.

PyReduce

A data reduction pipeline for echelle spectrographs (HARPS, UVES, XSHOOTER, CRIRES+, JWST/NIRISS, ANDES, MOSAIC, NEID, and more).

Based on the REDUCE package. See the papers:

• Piskunov & Valenti (2001) doi:10.1051/0004-6361:20020175
• Piskunov, Wehrhahn & Marquart (2021) doi:10.1051/0004-6361/202038293

Installation

# Using uv (recommended)
uv add pyreduce-astro

# Or pip
pip install pyreduce-astro

For development:

git clone https://github.com/ivh/PyReduce
cd PyReduce
uv sync
uv run reduce-build

No wheel for your platform, or the C extension won't build?

Extraction also runs in pure Python. Set PYREDUCE_EXTRACTION=numpy (or pass --extraction numpy) and nothing needs compiling — numpy and scipy are already core dependencies:

PYREDUCE_EXTRACTION=numpy uv run reduce run UVES -t HD132205

It is ~2x slower than the C extension and produces bit-identical output files. PYREDUCE_EXTRACTION=numba is ~1.5-1.8x with uv sync --extra numba installed. See Extraction Backends.

Quick Start

# Download sample data
uv run reduce download UVES

# Run reduction
uv run reduce run UVES -t HD132205 --steps bias,flat,trace,science

# Or run individual steps
uv run reduce bias UVES -t HD132205
uv run reduce flat UVES -t HD132205

Or use the Python API:

from pyreduce.pipeline import Pipeline

Pipeline.from_instrument(
    instrument="UVES",
    target="HD132205",
    night="2010-04-01",
    channel="middle",
    steps=("bias", "flat", "trace", "science"),
).run()

Plotting

Control plotting with environment variables:

# Save plots to files (headless/CI)
PYREDUCE_PLOT=1 PYREDUCE_PLOT_DIR=/tmp/plots PYREDUCE_PLOT_SHOW=off uv run reduce run ...

# Show all plots at end (browser via webagg)
MPLBACKEND=webagg PYREDUCE_PLOT=1 PYREDUCE_PLOT_SHOW=defer uv run reduce run ...

See How To for details.

Documentation

Full documentation at ReadTheDocs.

Output

PyReduce creates .fits files (standard FITS with binary table extension). Headers include original keywords plus PyReduce-specific ones prefixed with e_.