  We present new ATCA multi-wavelength radio measurements (range 2.1-21.2 GHz)
of the early-type magnetic star rho Oph A, performed in March 2019 during 3
different observing sessions. These new ATCA observations evidence a clear
rotational modulation of the stellar radio emission and the detection of
coherent auroral radio emission from rho Oph A at 2.1 GHz. We collected
high-resolution optical spectra of rho Oph A acquired by several instruments
over a time span of about ten years. We also report new magnetic field
measurements of rho Oph A that, together with the radio light curves and the
temporal variation of the equivalent width of the HeI line (lambda=5015
Angstrom), were used to constrain the rotation period and the stellar magnetic
field geometry. The above results have been used to model the stellar radio
emission, modelling that allowed us to constrain the physical condition of rho
Oph A's magnetosphere. Past XMM measurements showed periodic X-ray pulses from
rho Oph A. We correlate the X-ray light curve with the magnetic field geometry
of rho Oph A. The already published XMM data have been re-analyzed showing that
the X-ray spectra of rho Oph A are compatible with the presence of a
non-thermal X-ray component. We discuss a scenario where the emission phenomena
occurring at the extremes of the electromagnetic spectrum, radio and X-ray, are
directly induced by the same plasma process. We interpret the observed X-ray
and radio features of rho Oph A as having an auroral origin.
