Directed by Cameron Crowe, the 2011 documentary “The Union” (8 p.m., HBO) chronicles the making of Elton John and Leon Russell’s collaborative album of the same name.

”Union” finds John at a crossroads. Too young and energetic to retire, he does not feel like churning out just any old album. He’s resisted pressure to make a Motown collection. And he bristles at the suggestion that he record Christmas music.

While on a safari, John heard some old songs by Russell that moved him to tears. Like John, Russell was a fixture of the pop music scene of the early 1970s. Both performed at the fabled Troubadour club in Los Angeles. But while Russell co-wrote the plaintive anthem (and Carpenters hit) “Superstar,” he never became one. When John called him to do an album together, he was playing very small clubs. It was the first time they had spoken in 38 years.

As John makes clear, the collaboration should be good for Russell, bringing him commercial success and introducing a whole new generation to his music. John is also savvy enough to know that a return to the blues- and gospel-inflected pop of his own ’70s hits might connect with his baby boomer fans. Russell accepts this charitable gesture with stoic grace.

The film offers a rare chance to watch John and Russell work together with producer T-Bone Burnett. Other artists, including Stevie Nicks, Brian Wilson and producer Don Was, visit them along the way.

”Union” features vintage clips of the two singers in their heyday and informs us of how many classic songs and albums Russell contributed to as a studio musician — from the Beach Boys’ “Fun, Fun, Fun” to Frank Sinatra’s “Strangers in the Night.”

• Spend Groundhog Day with an “American Beaver” (6 a.m.-2 a.m., National Geographic Wild) marathon. Or watch Bill Murray pursue Andie MacDowell for an eternity in the 1993 comedy fantasy “Groundhog Day” (7 p.m. and 9:30 p.m., CMT).

Tonight’s other highlights

• Leonard feels estranged from Sheldon on “The Big Bang Theory” (7 p.m., CBS).

• Auditions continue on “American Idol” (7 p.m., Fox).

• Jack plays hardball on “30 Rock” (7 p.m., NBC).

• A run of bad luck on “Person of Interest” (8 p.m., CBS).

• Jury duty on “The Office” (8 p.m., NBC).

• A lost lucky charm on “The Finder” (8 p.m., Fox).

• Might-have-beens abound on “Grey’s Anatomy” (8 p.m., ABC).

• Murder stalks the apparel trade on “The Mentalist” (9 p.m., CBS).

• Victor Garber guest-stars on “The Firm” (9 p.m., NBC).

• A patient makes Sheldon face his own trauma on “Private Practice” (9 p.m., ABC).

• The guys carry the torch for a local cause on “Unsupervised” (9:30 p.m., FX).

• “Independent Lens” (9 p.m., PBS, check local listings) presents “Daisy Bates: First Lady of Little Rock,” a profile of a civil rights activist and early feminist.