Hans Ulrich Obrist , one of the art world’s great curators, is more deeply connected with artists than most could dream: he has estimated that he’s recorded over 2,000 hours worth of interviews with artists, and he regularly posts handwritten notes from painters, sculptors, and filmmakers whose studios he’s visited. But one artist has regularly refused his requests for a studio visit, and that artist is one of the most secretive painters still alive today. In an interview with the Wall Street Journal , Obrist said that he has never been able to successfully get a studio visit with Jasper Johns , the painter most famous for Flag , his 1954–55 work depicting an American flag in encaustic.…