The paper by Tarnopolski and Bzowski investigates the influence of wavelength-dependent solar radiation pressure on the distribution of neutral interstellar hydrogen in the inner heliosphere. They construct a model to describe the evolution of the solar Lyman-α line profile with solar activity and modify an existing test-particle code to account for the dependence of radiation pressure on radial velocity. The results show that discrepancies between the classical and Doppler models appear between 5 and 3 AU from the Sun, increasing towards the Sun from a few percent to a factor of 1.5 at 1 AU. The classical model overestimates the density everywhere except for a 60° cone around the downwind direction, where a density deficit is observed. The magnitude of these discrepancies depends on the phase of the solar cycle but is weakly influenced by the parameters of the gas at the termination shock. For in situ measurements of neutral atoms at 1 AU, such as those planned for the IBEX mission, the Doppler correction is necessary to account for the modifications in both the magnitude and direction of the local flux by a few km/s and degrees, respectively. This correction is crucial for accurate determination of the bulk velocity vector at the termination shock. The study concludes that the Doppler correction is significant for in situ observations of neutral H populations and their derivatives in the inner heliosphere.The paper by Tarnopolski and Bzowski investigates the influence of wavelength-dependent solar radiation pressure on the distribution of neutral interstellar hydrogen in the inner heliosphere. They construct a model to describe the evolution of the solar Lyman-α line profile with solar activity and modify an existing test-particle code to account for the dependence of radiation pressure on radial velocity. The results show that discrepancies between the classical and Doppler models appear between 5 and 3 AU from the Sun, increasing towards the Sun from a few percent to a factor of 1.5 at 1 AU. The classical model overestimates the density everywhere except for a 60° cone around the downwind direction, where a density deficit is observed. The magnitude of these discrepancies depends on the phase of the solar cycle but is weakly influenced by the parameters of the gas at the termination shock. For in situ measurements of neutral atoms at 1 AU, such as those planned for the IBEX mission, the Doppler correction is necessary to account for the modifications in both the magnitude and direction of the local flux by a few km/s and degrees, respectively. This correction is crucial for accurate determination of the bulk velocity vector at the termination shock. The study concludes that the Doppler correction is significant for in situ observations of neutral H populations and their derivatives in the inner heliosphere.