Surface reflectance properties of distant Solar system bodies

The recent discoveries of over 40 new objects with orbits beyond 30 au represent the first sampling of a reservoir of objects lying beyond Neptune, known as the Kuiper Belt (or Edgeworth-Kuiper Belt), which may be a source of short-period comets and Centaurs (objects whose orbits cross those of the giant planets). There are very few observations from which to derive physical properties of these Kuiper Belt objects (KBOs) due to their faintness and the concentration on discovery rather than follow-up, although optical and near-IR photometry of the few brightest KBOs and Centaurs shows a diversity from neutral to extremely red colours. We present new BVRI photometry of five KBOs (1994JQ1, 1995DC2,1994JR1, 1995DA2 and one undesignated new KBO) and the Centaur object 1995DW2. With the current small sample, we find no compelling evidence for a correlation of colours with orbital zones, and consequently no clear mechanism to explain this diversity in terms of the irradiation mantle model.