Highlights 9/21 to 9/27

“Celtic Thunder” at 7 p.m. Sunday features five male vocalists taking part in a celebration of Celtic heritage.

The IRA expert shares strategies viewers can implement to safeguard their retirement savings on “Stay Rich Forever & Ever With Ed Slott” at 9 p.m. Sunday.

“Lifeguard” follows the influence of family, religion, and anti- communism on Ronald Reagan from his youth to presidency in “American Experience” at 8 p.m. Monday.

Flutist James Galway joins conductor Lorin Maazel in a performance of Tchaikovsky’s Fourth Symphony in “Live from Lincoln Center” at 10 p.m. Monday

“Nova” at 7 p.m. Tuesday reveals the dark secrets of black holes, from their birth to their destructive waves of energy.

The four brothers who founded the movie studio in 1923 and its early films and stars are explored in part one of “The Warner Bros. Story” in “American Masters” at 8 p.m. Tuesday. Warren Beatty and other industry insiders discuss the movie studio’s history and its best films in part two of “The Warner Bros. Story” in “American Masters” at 8 p.m. Wednesday.  Part three of “The Warner Bros. Story” in “American Masters” at 8 p.m. Thursday features Clint Eastwood, George Clooney and great movie clips.

Jim Lehrer interviews George W. Bush, Dick Cheney, Joe Lieberman, John Kerry and Al Gore in “Debating Our Destiny II” at 10 p.m. Tuesday.

“Killer Stress: National Geographic” at 7 p.m. Wednesday reveals just how measurable and dangerous exposure to stress response can be.

John Mayer performs on the heels of his tour for his Grammy-winning album, Continuum, in “Austin City Limits” at 10 p.m. Wednesday and 11 p.m. Friday.

“Texas Monthly Talks” at 7 p.m. Thursday speaks with Houston-born musician Billy Gibbons, whose look is as distinctive as the songs he’s written and played with ZZ Top.

“Docubloggers” at 7:30 p.m. Thursday takes a peek at some local baby bald eagles before they take flight, and meets with Sheila Smith and her 75 cats at the Shadow Cats Sanctuary.

Directed by Hector Galan, “Los Lonely Boys Cottonfields and Crossroads” at 9 p.m. Thursday tells the story of the band from San Angelo. Los Lonely Boys have rocked their way to the top of the American music industry, determined to fulfill their father’s long-held dream.

“Spain… On the Road Again” at 10 p.m. Friday follows Gwyneth Paltrow and Mario Batali as they visit Madrid and Toledo and have a cooking lesson with a top chef.

“Austin City Limits” at 7 p.m. Saturday presents performances from San Francisco’s Hardly Strictly Bluegrass Festival in Golden Gate Park.