“Most Haunted Live: Gettysburg” (8 p.m. to 3 a.m., Travel Channel): Maybe it’s

“Most Haunted Live: Gettysburg” (8 p.m. to 3 a.m., Travel Channel): Maybe it’s because Halloween is approaching, but whatever the reason, Travel Channel’s “Most Haunted” presents its first live broadcast — and its longest — Friday. Yvette Fielding and the rest of the “Most Haunted” investigative team conduct a seven-hour paranormal exploration in the haunted town of Gettysburg, Pa., where for three days in July 1863, the South and the North met in what became the deadliest clash of the Civil War, claiming more than 40,000 lives. How many lost souls linger there to this day? And are they still seeking their 15 minutes of TV fame? Maybe viewers can find out by monitoring live webcams and communicating with the team via the message boards and text messaging.

“The Starter Wife” (9 p.m., USA): “The Starter Wife” generated solid ratings as a miniseries last year. Now it returns as a full-fledged weekly drama featuring Debra Messing (”Will & Grace”) as a woman trying to find her footing after her movie executive husband ditches her. Judy Davis and Chris Diamantopoulos also star.

“Eleventh Hour” (10 p.m., CBS): You’d think this mystery series — about a team of experts called into crisis situations when conventional thinking fails — would air at, oh, maybe, 11 p.m.?