New York ? Lately your attention is drawn to the finger-pointing in Washington over who knew what before the Sept. 11 attacks. Your anxiety flares at word that the Statue of Liberty or the Brooklyn Bridge could be next.

But here’s a way to stay focused on what matters. Watch “In Memoriam: New York City, 9/11/01,” premiering at 8 p.m. Sunday on HBO. And tape it.

Then, every month or two, when your resolve feels shaky and your anger is liable to subside, pull out this magnificent reminder and watch it again (it’s just an hour).

“In Memoriam” can serve you not only as the definitive filmed record of that dreadful day, but as a booster shot to galvanize you for the days ahead.

You’d rather not revisit those events? Hear former Mayor Rudolph Giuliani, who in the film recommends staying focused on the tragedy, even as you move on.

“If you censor it too much, if you try to find too many euphemisms for what happened,” he says, then you may be hard pressed “to prevent it from happening in the future.”

Granted, this isn’t the first filmed retrospective of the attacks on the World Trade Center. In March, CBS gained a lot of attention for its simply titled “9/11,” which showcased footage of firefighters’ rescue efforts inside one of the center’s towers as part of a portrait of a New York firehouse.

By contrast, “In Memoriam” is all about the tragedy.

And whereas all of “9/11” was shot by filmmakers Gedeon and Jules Naudet, the HBO documentary reflects diverse points of view: still and video imagery from more than 100 sources, including TV networks, news agencies (such as The Associated Press) and scores of individual eyewitnesses who happened to have a camera within reach.

The twin towers attack was “the most documented event in human history,” as the film declares straight away. The far-flung video and audio (with each clip duly credited) gives dimension to the storytelling, and democratizes it with many, varied accounts: video from an NYPD helicopter as it circles damaged Tower One, helpless to assist; footage of workers in the lower lobby trudging up stalled escalators to safety, and the devastation captured from a train as it crosses the East River, its conductor heard announcing a route change “until further notice.”

In sum, the film reaches an illuminating, ghastly consensus.

Giuliani plays an important role in tying it all together. Not only is he seen on the front line of what he expected to be “a quiet day,” but also, months later, as an on-camera guide to the crush of events.

Repeatedly he displays perfect pitch for voicing what everybody feels. With glistening eyes at one point he muses, “We’ll never know all the heroes,” among whom he imagines “the person who maybe, in the last moments, comforted people when all of them knew they were gonna die.”

The most disturbing imagery (seen as video as well as in a photo sequence) shows tower occupants plunging to certain death. But probably the most heartbreaking moments of “In Memoriam” are heard, not seen: the posthumous messages on answering machines.

“Neil, it’s Brian,” one farewell begins. “A plane crashed into the trade center. It’s on fire and I’m in it and I can’t breathe.”

The scope of “In Memoriam” reaches beyond Sept. 11, but just far enough to acknowledge its grim aftermath: people with photos and handbills seeking word of missing loved ones; rescuers digging at ground zero; the funerals.

“We have to cry,” says Giuliani at a memorial service, admitting he had cried on the way to the church. But then he adds: “The tears have to make you stronger. Every time you cry, you have to remember that we’re right and they’re wrong.”