Top: C/2024 E1 position along the parallax axis after subtracting the fitted polynomial sky motion, with the fitted diurnal-parallax model (line). Middle: measured parallax semi-amplitude versus known distance from the spacecraft for the 13 validation targets; the solid line is the expected π_GEO = R_GEO/Δ with no free parameters, star-shaped markers are fits to per-frame positions measured by eye (legend names the measurer), circles are fits to software-measured positions, and the dashed line is the ﹩0\mathop{.}\limits^{^{\prime\prime} }8﹩ median field-star floor measured through the identical chain. Bottom: residuals from the expected line, in percent.