Authors Stephen King, J.K. Rowling and John Irving are scheduled to appear together tonight at Radio City Music Hall in New York to read from their books as a charity fundraiser for two groups. Rowling was in the United States for the first time since 2000 to take part in the reading for charity. “An Evening With Harry, Carrie and Garp” is supporting The Haven Foundation, King’s choice, which helps performing artists whose accidents or illnesses have left them uninsured and unable to work, and Doctors Without Borders, Rowling’s pick, a humanitarian group that delivers emergency aid in more than 70 countries. King, who came up with the idea after doing a reading for one of Irving’s charities, said they hoped to raise at least $250,000 for each group