Can we detect a supertranslated black hole?

We attempt to address the question of whether standard tests of general relativity can detect the presence of a black hole carrying a supertranslation field. In this regard, we study the photon sphere of a dynamical black hole carrying a supertranslation hair. We find that the dynamics of the photon sphere is quite subtle and it may offer an opportunity to differentiate a supertranslated black hole from its bald counterpart. This represents a first step towards understanding the observational signatures of a supertranslated dynamical black hole.