  In the recent paper by Sokolov et al. (Int. J. of Heat and Mass Transfer 176,
2021, 121442) ballistic heat propagation in 1D harmonic crystal is considered
and the properties of the exact discrete solution and the solution of the
ballistic heat equation introduced by Krivtsov are numerically compared. The
aim of this note is to demonstrate that the latter continuum fundamental
solution can be formally obtained as the slow time-varying component of the
large-time asymptotics for the exact discrete solution on a moving point of
observation.
