Joan Quigley, a San Francisco socialite and writer who became famous as the astrologer who advised President Reagan and First Lady Nancy Reagan in the 1980s, has died. Mrs. Quigley, who was fashionable and social but had a flinty stare, spent seven years as the White House astrologer, advising the Reagans on everything from when to schedule Air Force One takeoffs to the best time for summit meetings and surgeries. “Sometimes I would talk with Nancy for three hours a day,” Mrs.