On May 23, 2005, ABC News announced that Robin Roberts would be promoted from newsreader to co-anchor of "Good Morning America", joining Gibson and Sawyer. Roberts had previously served as a regular substitute for Gibson and Sawyer when either of them were on vacation or on assignment. On November 3, 2005, "Good Morning America" celebrated its 30th anniversary with retrospectives on and clips from the show's history and by decorating Times Square. Former co-hosts Hartman and Lunden, along with former meteorologist Spencer Christian, were among the guests of honor. Hartman signed off the show that day with his trademark close: "From all of us, make it a good day." That same day, "Good Morning America" became the first network morning news program to begin broadcasting in high-definition television.