Description
The following code is unexpectedly slow because the ecliptic transforms directly call ERFA routines rather than using the interpolation machinery:
import numpy as np
from astropy import units as u
from astropy.coordinates import GeocentricTrueEcliptic, SkyCoord
from astropy.coordinates.erfa_astrom import ErfaAstromInterpolator, erfa_astrom
from astropy.time import Time
erfa_astrom.set(ErfaAstromInterpolator(30 * u.day))
n = 1_000_000
obstime = Time("2025-01-01") + np.linspace(0, 365, n) * u.day
target_coord = SkyCoord(np.linspace(0, 360, n, endpoint=False) * u.deg, 0 * u.deg)
target_coord.transform_to(GeocentricTrueEcliptic(equinox=obstime))Expected behavior
Should go fast!
How to Reproduce
See code sample above.
Versions
platform
--------
platform.platform() = 'macOS-26.7-arm64-arm-64bit-Mach-O'
platform.version() = 'Darwin Kernel Version 25.6.0: Tue Aug 18 17:51:35 PDT 2026; root:xnu-12377.161.15.700.19~2/RELEASE_ARM64_T6031'
platform.python_version() = '3.14.7'
packages
--------
astropy 8.0.1
numpy 2.5.3
scipy 1.18.1
matplotlib 3.11.2
pandas --
pyerfa 2.0.1.5
Description
The following code is unexpectedly slow because the ecliptic transforms directly call ERFA routines rather than using the interpolation machinery:
Expected behavior
Should go fast!
How to Reproduce
See code sample above.
Versions