Rendiment

Què

Converts sky positions from RA/Dec (equatorial) to ecliptic longitude/latitude, using the obliquity of the ecliptic.

Per què

Ecliptic coordinates are natural for solar system objects. The transform depends on the obliquity model used.

Interpretació

Lower separation = better agreement with ERFA's IAU 2006 obliquity model.

Contracte de rendiment

Timed scope: obliquity evaluation + rotation per epoch. Input parsing is outside the timed loop.

Què

Rotates a direction vector from the ICRS celestial reference frame to the True-of-Date frame using the Bias-Precession-Nutation (BPN) matrix.

Per què

This is the fundamental coordinate transformation used in astrometry. Differences indicate how well each library models Earth's axis wobble.

Interpretació

Lower error = closer to ERFA's IAU 2006/2000A model. Siderust uses simpler Meeus precession + IAU 1980 nutation, so some offset is expected.

Contracte de rendiment

Timed scope: matrix construction + single matrix-vector multiply per epoch. Input JD conversion and output formatting are outside the timed loop. All adapters construct the full BPN matrix from scratch.

Què

Converts celestial RA/Dec to local azimuth/altitude for a ground observer, using sidereal time and spherical trigonometry.

Per què

This is the 'where do I point my telescope?' calculation. Accuracy depends on the GAST (sidereal time) model used.

Interpretació

Lower separation = better. Differences mainly arise from GAST model choice. libnova uses a different sidereal-time model from SOFA/IERS and is not rankable for accuracy in this experiment.

Contracte de rendiment

Timed scope: GAST computation + spherical trig per epoch+location. Input parsing (JD, RA/Dec, lon/lat) is outside the timed loop.

Què

Computes GMST (how far the Earth has rotated relative to the stars) and ERA (the raw rotation angle) at given epochs.

Per què

Time-scale conversions underpin all ground-based astronomical observations. Small errors here compound in coordinate transforms.

Interpretació

Lower error = better agreement with ERFA's IAU 2006 polynomial. Libnova uses Meeus formula which differs at the arcsecond level.

Contracte de rendiment

Timed scope: GMST/ERA evaluation per epoch pair (JD_UT1, JD_TT). Input parsing and output serialisation are outside the timed loop. Astropy adapter uses public astropy.time APIs with an explicit UT1 override derived from the benchmark input pair.

Què

Solves Kepler's equation M = E - e·sin(E) for the eccentric anomaly E, then computes the true anomaly ν. Tests convergence across eccentricities.

Per què

Kepler's equation is fundamental to orbital mechanics. Different solvers (Newton-Raphson vs bisection) have different convergence properties.

Interpretació

Lower residual = better convergence. Libnova's bisection method converges to ~1e-6 deg, while Newton-Raphson methods reach ~1e-15 rad.

Contracte de rendiment

Timed scope: iterative solver per (M, e) pair. Input parsing is outside the timed loop. This is a numerical convergence benchmark, not an ephemeris accuracy claim.