JPL DE421+plu021 ephemerides offsets of Pluto in right ascension (triangles) and declination (squares) as a function of time, in the sense observed minus ephemeris. The 16 Pluto positions were determined from fittings of past occultations in 2005−2013, taking as reference the UCAC4-based star positions that we derived from OPD observations specifically made for these stars (see Table 5).