  Two-particle correlation functions are calculated for bosons emitted from a
localized thermal source (the ``glow'' of a ``hot spot''). In contrast to
existing work, non-equilibrium effects up to first order in gradients of the
particle distribution function are taken into account. The spectral width of
the bosons is shown to be an important quantity: If it is too small, they do
not equilibrate locally and therefore strongly increase the measured
correlation radius. In memoriam of Eugene Wigner and Hiroomi Umezawa.
