  The magnetic hyperfine structure constants have been calculated for low-lying
levels in neutral gold atom and gold-like ion of mercury taking into account
Bohr--Weisskopf (BW) effect. BW effect is represented as a product of atomic
and nuclear ($d_\mathrm{nuc}$) factors. We have calculated the atomic factors,
which enable one to extract BW-correction values for far from stability gold
nuclei from the experimental data. The possible uncertainty of our atomic
calculations have been estimated by the comparison with the available
experimental data. It has been shown that the standard single-particle approach
in $d_\mathrm{nuc}$ calculation reasonably well describes experimental data for
$11/2^-$ gold isomers and $3/2^+$ ground state of $\rm ^{199}Au$. At the same
time, it fails to describe the hyperfine constant in $^{197}\mathrm{Au}$. This
indicates the more pronounced configuration mixing in $\rm ^{197}Au$ than in
$\rm ^{199}Au$.
