  The multi-wavelength study of old (>100 Myr) radio pulsars holds the key to
understanding the long-term evolution of neutron stars, including the advanced
stages of neutron star cooling and the evolution of the magnetosphere.
Optical/UV observations are particularly useful for such studies because they
allow one to explore both thermal and non-thermal emission processes. In
particular, studying the optical/UV emission constrains temperature of the bulk
of the neutron star surface, too cold to be measured in X-ray observations.Aim
of this work is to identify the optical counterpart of the very old (166 Myr)
radio pulsar J0108-1431. We have re-analyzed our original VLT observations
(Mignani et al. 2003), where a very faint object was tentatively detected close
to the radio position, near the edge of a field galaxy. We found that the
backward extrapolation of the PSR J0108-1431 proper motion recently measured by
CHANDRA(Pavlov et al. 2008) nicely fits the position of this object. Based on
that, we propose it as a viable candidate for the optical counterpart to PSR
J0108-1431. The object fluxes (U =26.4+/-0.3; B =27.9; V >27.8) are consistent
with a thermal spectrum with a brightness temperature of 9X10^4 K (for R = 13
km at a distance of 130 pc), emitted from the bulk of the neutron star surface.
New optical observations are required to confirm the optical identification of
PSR J0108-1431 and measure its spectrum.
