  The motion of massless spinning test particles is investigated using the
Newman-Penrose formalism within the Mathisson-Papapetrou model extended to
massless particles by Mashhoon and supplemented by the Pirani condition. When
the "multipole reduction world line" lies along a principal null direction of
an algebraically special vacuum spacetime, the equations of motion can be
explicitly integrated. Examples are given for some familiar spacetimes of this
type in the interest of shedding some light on the consequences of this model.
