astropy-astronomy
Astronomical computations via Astropy. Use when: user asks about celestial coordinates, FITS files, or cosmological calculations. NOT for: telescope control or real-time observation planning.
Best use case
astropy-astronomy is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Astronomical computations via Astropy. Use when: user asks about celestial coordinates, FITS files, or cosmological calculations. NOT for: telescope control or real-time observation planning.
Teams using astropy-astronomy should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/astropy-astronomy/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How astropy-astronomy Compares
| Feature / Agent | astropy-astronomy | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Astronomical computations via Astropy. Use when: user asks about celestial coordinates, FITS files, or cosmological calculations. NOT for: telescope control or real-time observation planning.
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
SKILL.md Source
# Astropy Astronomy
Astronomical computations using Astropy.
## When to Use
- Celestial coordinate transforms (ICRS, Galactic, AltAz)
- Unit conversions for astronomical quantities
- Reading, writing, or inspecting FITS files
- Cosmological calculations (distances, ages, lookback times)
- Time system conversions (UTC, TAI, TDB, MJD, JD)
## When NOT to Use
- Telescope control or instrument automation
- Real-time observation planning or scheduling
- Image reduction or photometry pipelines (use photutils)
- N-body simulations
## Coordinate Transforms
```python
from astropy.coordinates import SkyCoord, EarthLocation, AltAz
from astropy.time import Time
import astropy.units as u
coord = SkyCoord(ra=10.684*u.deg, dec=41.269*u.deg, frame='icrs') # M31
coord_str = SkyCoord('00h42m44.3s', '+41d16m09s', frame='icrs')
# ICRS to Galactic
galactic = coord.galactic
print(f"l={galactic.l:.4f}, b={galactic.b:.4f}")
# Angular separation
c1 = SkyCoord(ra=10.684*u.deg, dec=41.269*u.deg)
c2 = SkyCoord(ra=11.0*u.deg, dec=41.5*u.deg)
sep = c1.separation(c2)
# AltAz (horizontal) coordinates
location = EarthLocation(lat=34.05*u.deg, lon=-118.25*u.deg, height=100*u.m)
time = Time('2026-03-15 03:00:00', scale='utc')
altaz = coord.transform_to(AltAz(obstime=time, location=location))
print(f"Alt={altaz.alt:.2f}, Az={altaz.az:.2f}")
```
## Unit Conversions
```python
import astropy.units as u
d = 10 * u.pc
print(d.to(u.lyr)) # parsecs to light-years
wav = 21 * u.cm
freq = wav.to(u.GHz, equivalencies=u.spectral())
wavelength = (13.6 * u.eV).to(u.nm, equivalencies=u.spectral())
```
## FITS File Handling
```python
from astropy.io import fits
with fits.open('image.fits') as hdul:
hdul.info()
header = hdul[0].header
data = hdul[0].data
hdu = fits.PrimaryHDU(data_array)
hdu.header['OBJECT'] = 'M31'
hdu.writeto('output.fits', overwrite=True)
```
## Cosmological Calculations
```python
from astropy.cosmology import Planck18 as cosmo
z = 1.0
d_L = cosmo.luminosity_distance(z) # luminosity distance
d_A = cosmo.angular_diameter_distance(z) # angular diameter distance
age = cosmo.age(z) # age of universe at z
lookback = cosmo.lookback_time(z) # lookback time
H_z = cosmo.H(z) # Hubble parameter at z
```
## Time Conversions
```python
from astropy.time import Time
import astropy.units as u
t = Time('2026-03-15 12:00:00', scale='utc')
print(t.jd, t.mjd, t.unix) # JD, MJD, Unix
print(t.tai, t.tdb) # TAI, TDB scales
now = Time.now()
```
## Quick One-liner
```bash
python3 -c "
from astropy.coordinates import SkyCoord; import astropy.units as u
c = SkyCoord(ra=83.633*u.deg, dec=22.014*u.deg)
print(f'Galactic: l={c.galactic.l:.3f}, b={c.galactic.b:.3f}')
"
```
## Best Practices
1. Always attach units to quantities using `astropy.units`.
2. Specify time scale explicitly (`utc`, `tai`, `tdb`).
3. Use `Planck18` as default cosmology unless otherwise specified.
4. Close FITS files or use context managers to prevent resource leaks.
5. Use `SkyCoord` for all coordinate work rather than manual trig.Related Skills
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