  The rotational constants and the nitrogen nuclear quadrupole coupling
constants of cis-3-aminophenol and trans-3-aminophenol are determined using
Fourier-transform microwave spectroscopy. We examine several $J=2\leftarrow{}1$
and $1\leftarrow{}0$ hyperfine-resolved rotational transitions for both
conformers. The transitions are fit to a rigid rotor Hamiltonian including
nuclear quadrupole coupling to account for the nitrogen nucleus. For
cis-3-aminophenol we obtain rotational constants of A=3734.930 MHz, B=1823.2095
MHz, and C=1226.493 MHz, for trans-3-aminophenol of A=3730.1676 MHz,
B=1828.25774 MHz, and C=1228.1948 MHz. The dipole moments are precisely
determined using Stark effect measurements for several hyperfine transitions to
$\mu_a=1.7735$ D, $\mu_b=1.5195$ D for cis-3-aminophenol and $\mu_a=0.5563$ D,
$\mu_b=0.5376$ D for trans-3-aminophenol. Whereas the rotational constants and
quadrupole coupling constants do not allow to determinate the absolute
configuration of the two conformers, this assignment is straight-forward based
on the dipole moments. High-level \emph{ab initio} calculations (B3LYP/6-31G^*
to MP2/aug-cc-pVTZ) are performed providing error estimates of rotational
constants and dipole moments obtained for large molecules by these theoretical
methods.
