e New York Times has appointed op-ed columnist Frank Rich as associate editor, saying he will return to the Arts and Leisure section to write a weekly column and help plan coverage. The Times also named David Shipley editor of the op-ed page. Rich, who is also a senior writer for The New York Times Magazine, will work alongside Steven Erlanger, who was recently named cultural news editor, the newspaper said Wednesday. He also will write a cultural essay for the front page of the Sunday Arts section, beginning this spring. Rich, 53, joined the Times as chief theater critic in 1980. In 1994, he became one of the newspaper's columnists. He was appointed a senior writer for the magazine in 1999, writing longer articles and commentaries on the arts and entertainment. Shipley, 39, was deputy editor of the op-ed page, and previously was senior editor of the magazine. He succeeds Terry Tang, 44, who is joining the paper's news department. Christine Kay, 38, an assistant editor on the Times metropolitan news desk, will become deputy Op-Ed editor. Shipley joined the Times in 1997 after serving as special assistant and senior speechwriter for President Clinton from 1995-199