  (Abridged) The Long Wavelength Spectrometer (LWS) onboard the Infrared Space
Observatory (ISO) observed the four large main-belt asteroids (1) Ceres, (2)
Pallas, (4) Vesta, and (10) Hygiea multiple times. The photometric and
spectroscopic data cover the wavelength range between 43 and 197 um, and are a
unique dataset for future investigations and detailed characterisations of
these bodies. The standard ISO archive products, produced through the last
post-mission LWS pipeline, were still affected by instrument artefacts. Our
goal was to provide the best possible data products to exploit the full
scientific potential of these observations. We performed a refined reduction of
all measurements, corrected for various instrumental effects, and re-calibrated
the data. We outline the data reduction process and give an overview of the
available data and the quality of the observations. We apply a thermophysical
model to the flux measurements to derive far-IR based diameter and albedo
values of the asteroids. The measured thermal rotational lightcurve of (4)
Vesta is compared to model predictions. The absolute photometric accuracy of
the data products was foubd to be better than 10%. The calibrated spectra will
serve as source for future mineralogical studies of dwarf planets and dwarf
planet candidates.
