  Advances in laser spectroscopy of superheavy ($Z>100$) elements enabled
determination of the nuclear moments of the heaviest nuclei, which requires
high-precision atomic calculations of the relevant hyperfine structure (HFS)
constants. Here, we calculated the HFS constants and energy levels for a number
of nobelium (Z=102) states using the hybrid approach, combining linearized
coupled-cluster and configuration interaction methods. We also carried out an
extensive study of the No energies using 16-electron configuration interaction
method to determine the position of the (5f^{13}7s^2 6d) and (5f^{13}7s^2 7p)
levels with a hole in the 5f shell to evaluate their potential effect on the
hyperfine structure calculations of the low-lying (5f^{14}7s6d) and
(5f^{14}7s7p) levels. We find that unlike the case of Yb, the mixing of the
low-lying levels with filled and unfilled f shell is small and does not
significantly influence their properties. The resulting HFS constants for the
5f^{14}7s7p 1P1 level, combined with laser-spectroscopy measurement, were used
to extract nobelium nuclear properties [S. Raeder et al., Phys. Rev. Lett. 120,
232503 (2018)]
