Ottawa’s National Arts Centre Orchestra has announced that music director Pinchas Zukerman will take a half-season sabbatical from the ensemble, effective with the start of the new year. He was scheduled to conduct five more concerts in the current season, but the NACO will find guest conductors to cover those dates. The centre says it fully expects Zukerman, whose current contract is up at the end of the 2006-07 season, to return in fall 2006, but news of the sabbatical came as a surprise to the orchestra’s musicians.