The eight-year liaison of George Sand (Judy...

The eight-year liaison of George Sand (Judy Davis), the most popular and notorious woman writer of the early 19th Century and composer Frederic Chopin (Hugh Grant) is at the center of the 1991 Impromptu (KCET, KPBS Sunday at 9 p.m., 8 p.m. on KVCR). Other geniuses of the day --Delacroix (Ralph Brown) and Alfred de Musset (Mandy Patinkin) are also around, but not acting as if they were famous.

The 1950 Rio Grande (KCAL Sunday at 9 p.m.), the final film in John Ford’s celebrated cavalry trilogy, centers on an estranged father (John Wayne) and son (Claude Jarman Jr.).

The 1986 Aliens (KTTV Monday at 8 p.m.) is a perfectly honorable sequel to the 1979 “Alien”--taut, inexorably paced yet not the equal of the original in cardiac-arrest value, if only because stainless-steel teeth, repulsiveness and slime have gone about as far as they can go. It’s certainly successful when Sigourney Weaver is around, which, fortunately, is most of the time. Weaver returns to “Alien” territory when she learns there is a space colony there, with more human fodder for the dreaded aliens.

The combination of the late director Don Siegel and Clint Eastwood was so potent that the 1971 Dirty Harry (KCOP Thursday at 8 p.m.) has become a classic example of the kind of rabble-rousing film you ought to hate but find hard to resist. This was Eastwood’s first time out as that violent, scrappy San Francisco cop who doesn’t hesitate taking the law into his own hands to nab a Zodiac-like killer.

La Bamba (KCOP Saturday at 4 p.m.), Luis Valdez’s 1987 film biography of ‘50s rock ‘n’ roller Ritchie Valens, is as infectious as its music, an irresistible saga of how a teen-age Mexican-American (Lou Diamond Phillips) made it from a migrant farm worker background to three hit records by age 17. Especially memorable is Esai Morales as Ritchie’s troubled older half-brother.

Director Neil Jordan and writer David Mamet’s 1989 reworking of the 1955 We’re No Angels (KTLA Saturday at 8 p.m.), about escaped convicts (Robert De Niro, Sean Penn) disguised as priests in a ‘30s-era Northeast border town, has its charms, despite flaws.

Close Encounters of the Third Kind (KCOP Saturday at 8 p.m.), Steven Spielberg’s magical, mystical 1977 sci-fi film, stars Richard Dreyfuss and features wondrous special effects.

Lynn Littman’s unforgettable, uncompromising, understated 1983 Testament (KCET Saturday at 11 p.m.) is arguably the most powerful anti-war American film ever made. Jane Alexander is superb as a woman trying to hold her family together in the aftermath of a nuclear holocaust.