name: astropy
description: "Use Astropy core for astronomy units, coordinates, times, tables,
FITS/WCS files, modeling, statistics, visualization, cosmology, configuration,
and public CLIs."
metadata:
disco-role: operating
disable-model-invocation: true
license: BSD 3-Clause
Astropy Repo Skill
Use this skill when a task needs the Astropy core Python package for astronomy
or astrophysics analysis. Astropy is a CPU scientific-Python library; selected
workflows do not require GPU or accelerator backends. Use an installed Astropy
package and the bundled references/scripts here rather than reopening the
source repository.
Fast Start
import astropy
from astropy import units as u
print(astropy.__version__)
print((42 * u.km / u.s).to(u.m / u.s))
If plotting, fitting, convolution FFT paths, or common dataframe bridges are
needed, prefer installing the common optional set:
python -m pip install "astropy[recommended]"
Use astropy[all] only for broad optional integrations such as HDF5, Parquet,
S3/fsspec, Jupyter, or additional astronomy packages.
Route by Task
- For units, quantities, equivalencies, custom units, and physical constants,
read sub-skills/units-constants/SKILL.md.
- For
Time, timescales, SkyCoord, coordinate frames, transformations,
separations, matching, and observation geometry, read
sub-skills/time-coordinates/SKILL.md.
- For
Table/QTable, unified I/O, FITS, ASCII/ECSV, VOTable, HDF5/Parquet
notes, pandas/dataframe bridges, and table/FITS CLIs, read
sub-skills/tables-io/SKILL.md.
- For FITS WCS, pixel/world conversion, WCS validation,
NDData, CCDData,
masks, uncertainties, and image metadata containers, read
sub-skills/wcs-nddata/SKILL.md.
- For image normalization, intervals, stretches, WCSAxes, RGB output,
fits2bitmap, kernels, direct convolution, and FFT convolution, read
sub-skills/visualization-convolution/SKILL.md.
- For models, fitters, compound models, constraints, robust statistics,
histograms, time series, periodograms, and uncertainty distributions, read
sub-skills/modeling-stats-timeseries/SKILL.md.
- For cosmology realizations/classes, distances, ages, redshift inversion,
cosmology units, and serialization, read
sub-skills/cosmology/SKILL.md.
- For install/import checks, optional extras, config/cache, remote data/IERS,
logging/warnings, SAMP, and the general CLI catalog, read
sub-skills/cli-config-data/SKILL.md.
Shared References and Scripts
Operating Rules
- Keep units attached until a non-Astropy API requires raw arrays; then use
.to_value(unit) and record the unit.
- Be explicit about
format=, scale=, frame=, unit=, origin=, and
format names for I/O to avoid silent guessing.
- Use temporary files for smoke checks and never mutate user FITS/table files
unless the user explicitly requested that exact operation.
- For offline or reproducible tasks, disable or control remote downloads before
coordinate/time/IERS/name-resolution operations.
- Validate scientific transformations numerically: unit round-trips,
pixel/world round-trips, table read/write round-trips, fit residuals, or
cosmology unit checks.
- Route optional dependency errors to the nearest sub-skill first, then to the
root troubleshooting reference for install-level decisions.
Do Not Use This Skill For
- General NumPy/Pandas data processing without Astropy APIs, astronomy formats,
units, times, or coordinates.
- Maintaining the Astropy repository, release engineering, CI, or documentation
build workflows.
- Running broad Astropy test suites or benchmarks as a substitute for a focused
user workflow.
- SAMP services, remote data downloads, or file-mutating CLI operations without
explicit user approval and bounded temporary-file safeguards.