The diagrams employ horizontal (alt-az) coordinates with zenith at the top. The apparent
curved path of Venus is due to the Earth’s rotation. Unlike generic diagrams with
straight paths utilizing geocentric equatorial coordinates, those here show how the
transit will actually appear in the sky at specific locations. Due to the parallax
effect, event timings would vary among the locations even if adjusted to Universal
Time. Interpolation should suffice for observers at intermediate sites.
