  In arXiv:2311.03443 the authors have proposed an interesting framework for
studying holography in flat space-time. In this note we explore the
relationship between their proposal and the Celestial Holography. In
particular, we find that in both the massive and in the massless cases the
asymptotic boundary limit of the bulk time-ordered Green's function $G$ is
related to the Celestial amplitudes by an integral transformation. In the
massless case the integral transformation reduces to the well known
\textit{shadow transformation} of the celestial amplitude. Now the relation
between the asymptotic limit of $G$ and the celestial amplitudes suggests that
in asymptotically flat space-time if the scattering states are described by the
conformal primary basis (and it's analytic continuation in dimension $\Delta$)
then the boundary operators holographically dual to the (massless) bulk fields
are given by the \underline{shadow transformation} of the conformal primary
operators living on the celestial sphere. In other words, conformal primary
operators themselves are not boundary operators but their shadows are. This is
consistent with the fact that in celestial holography the boundary stress
tensor is given by the shadow transformation of the subleading soft graviton.
