NBC has given the go-ahead to "Later With Bob Costas," an interview show hosted by the sports announcer set to debut Aug. 22. The half-hour program will follow "Late Night With David Letterman," Monday through Thursday nights. Costas will interview personalities from all walks of life in an attempt to "find the real person behind the public image," an NBC spokesman said. Interviews may run as long as four nights, depending on the what the subject has to say. The show--produced by Dick Ebersole of "Saturday Night Live" and "Friday Night Videos" fame--will be shot in New York City during most of the year, moving to St. Louis during summer months to accommodate Costas' schedule.