Provenance and accuracy
Besselian elements are taken verbatim from
NASA/GSFC (F. Espenak), Five Millennium Canon of Solar Eclipses.
Nothing here is approximated or reconstructed. Local circumstances follow the
standard Besselian method (Meeus, Astronomical Algorithms, ch. 54);
solar altitude and azimuth are computed independently from Meeus ch. 25 and
corrected for refraction with Saemundsson's formula.
Predictions use the Moon's centre of mass and ignore the lunar limb profile,
which can move the path limits by 1–3 km and change duration by
1–3 s. Refraction near the horizon is an approximation and depends on
the actual air mass on the day. Elevation is read from
Terrain Tiles on AWS Open Data
(SRTM and NED), sampled at about 30 m; sharp summits read low, and the figure
can be overridden by typing one. Without the tile server the field stays manual and
defaults to the ellipsoid.
Computed times carry an uncertainty of a few seconds. Do not use them as the sole
trigger for removing eye protection. Take the reappearance of the photosphere as
your cue, not a clock.