We compute a large collection of string worldsheet correlators describing
light probes interacting with heavy black hole microstates. The heavy states
consist of NS5 branes carrying momentum and/or fundamental string charge. In
the fivebrane decoupling limit, worldsheet string theory on a family of such
backgrounds is given by exactly solvable null-gauged WZW models. We construct
physical vertex operators in these cosets, including all massless fluctuations.
We first compute a large class of novel heavy-light-light-heavy correlators in
the AdS$_3$ limit, where the light operators include those dual to chiral
primaries of the holographically dual CFT. We compare a subset of these
correlators to the holographic CFT at the symmetric product orbifold point, and
find precise agreement in all cases, including for light operators in twisted
sectors of the orbifold CFT. The agreement is highly non-trivial, and includes
amplitudes that describe the analogue of Hawking radiation for these
microstates. We further derive a formula for worldsheet correlators consisting
of $n$ light insertions on these backgrounds, and discuss which subset of these
correlators are likely to be protected. As a test, we compute a heavy-light
five-point function, obtaining precisely the same result both from the
worldsheet and the symmetric orbifold CFT. This paper is a companion to and
extension of [arXiv:2203.13828].
