  The bound states of the D1D5 brane system have a known gravitational
description: flat asymptotics, an anti-de Sitter region, and a 'cap' ending the
AdS region. We construct perturbations that correspond to the action of chiral
algebra generators on Ramond ground states of D1D5 branes. Abstract arguments
in the literature suggest that the perturbation should be pure gauge in the AdS
region; our perturbation indeed has this structure, with the nontrivial
deformation of the geometry occurring at the 'neck' between the AdS region and
asymptotic infinity. This 'non-gauge' deformation is needed to provide the
nonzero energy and momentum carried by the perturbation. We also suggest
implications this structure may have for the majority of microstates which live
at the cap.
