Astronomy
Stellar parallax
Two dates, one moving image, and a distance measured from completed exposures. Compare frames and separate parallax from proper motion.
What happens
Circular Earth orbit, fixed tangent plane, linear proper motion and independent Gaussian errors per coordinate. A synthetic teaching experiment, not a Gaia data reduction. The fit uses completed exposures only. Negative parallaxes are kept; weak positive estimates are not presented as reliable reciprocal distances. Quoted distance bounds invert p ±1σ and are not a distance posterior. Orbit distances, body sizes and luminous markers are schematic; the sky axes use the same mas scale. 1 mas = 0.001 arcsec. A six-month displacement depends on phase and need not equal 2p.
Equations used in the module
Equations p(arcsec) = 1 / d(pc) x = x₀ + μx t + p Px(t); y = y₀ + μy t + p Py(t) Px = sin(λ − L); Py = sin β cos(λ − L)
