  The near-Earth asteroid (25143) Itokawa was characterised in great detail by
the Japanese Hayabusa mission. We revisited the available thermal observations
in the light of the true asteroid properties with the goal to evaluate the
possibilities and limitations of thermal model techniques. In total, we used 25
published ground-based mid-infrared photometric observations and 5 so far
unpublished measurements from the Japanese infrared astronomical satellite
AKARI in combination with improved H-G values. Our thermophysical model (TPM)
approach allowed us to determine correctly the sense of rotation, to estimate
the thermal inertia and to derive robust effective size and albedo values by
only using a simple spherical shape model. A more complex shape model, derived
from light-curve inversion techniques, improved the quality of the predictions
considerably and made the interpretation of thermal light-curve possible. The
radiometrically derived effective diameter value agrees within 2% of the true
Itokawa size value. The combination of our TPM and the final Itokawa in-situ
shape model was then used as a benchmark for deriving and testing radiometric
solutions. The consolidated value for the surface-averaged thermal inertia is
700 $\pm$ 200 Jm$^{-2}$s$^{-0.5}$K$^{-1}$. We found that even the high
resolution shape models still require additional small-scale roughness in order
to explain the disk-integrated infrared measurements. Our description of the
thermal effects as a function of wavelengths, phase angle, and rotational phase
facilitates the planning of crucial thermal observations for sophisticated
characterization of small bodies, including other potentially hazardous
asteroids. Our analysis shows the power of radiometric techniques to derive the
size, albedo, thermal inertia, and also spin-axis orientation from small sets
of measurements at thermal infrared wavelengths.
