EVOLUTION OF THE ORBIT OF COMET 46P WIRTANEN DURING 1947-2013/

The nucleus' surface of comet P/Wirtanen is to be investigated in 2011 during the ROSETTA space mission. An attempt to link all the observed apparitions of the comet is presented. Nongravitational effects in th e comet's motion have been examined using several ways. The best solut ion has been found for forced precession model of the comet by express ing the Marsden's nongravitational parameters A(1), A(2), A(3) in term s of angular parameters of the rotating and precessing oblate cometary nucleus. This model allowed us to determine five nongravitational par ameters: A, eta, I, phi, and f(p), together with six corrections to th e orbital elements, solving observational equations by the least squar es method. Finally, all the seven recorded apparitions of the comet we re linked using 67 positional observations covering the period 1948-19 91; the mean RMS residual is equal to 2 ''.33. The past and future com et's orbit evolution is presented.