A Kinematic-Medium Model of Optical Propagation Near the Sun: A Newtonian-Style Dynamical Baseline, Coronal Plasma Dispersion, and a Prospective Eclipse Test

This paper develops a testable phenomenological framework for optical propagation near the Sun. The framework adopts an explicitly stated Newtonian-style transverse-acceleration prescription as a gravitational baseline and treats the solar-coronal plasma response as a separate propagation contribution. The spatial geometry is Euclidean; local Lorentz transformations are used only to relate electromagnetic quantities between the plasma rest frame and the observer frame. The result is a flat-spacetime kinematic model with Euclidean spatial sections, not a purely Galilean theory with absolute time. For an unperturbed ray with impact parameter b, the adopted effective acceleration law yields alpha_N = 2GM_sun/(c^2 b). In the cold, collisionless, unmagnetized plasma limit, spatial density gradients can still refract the ray. For an illustrative Leblanc-Dulk-Bougeret outer-coronal density law and lambda = 550 nm, the estimated plasma deflection at b = 10 R_sun is outward with magnitude of order 10^-13 arcsec. A prospective programme for the total solar eclipse of 2 August 2027 is outlined, with M44 considered as a candidate background field. The manuscript defines a falsifiable research programme.