Jeffrey Straus and Tim Tompkins are New York’s “Keepers of the Ball.”

The title is informal, of course, one that the Scarsdale-born Mr. Straus and Mr. Tompkins, a Philadelphian, often chuckle over. But it accurately describes their job.

The two men must preserve and prepare a 1,070-pound Waterford geodesic sphere to drop 77 feet on a steel pole atop One Times Square in 60 seconds Saturday night. The ball is 6 feet in diameter; it has 696 lights and 90 rotating pyramid mirrors, all of which are computer-programmed to produce a kaleidoscopic light show.

And when the ball arrives at the base of the pole after a countdown that resonates around the world, a new year will have been ushered in — on the East Coast, at least.

“Our entire year truly boils down to this moment,” Mr. Straus, president of Countdown Entertainment, said yesterday.

“It’s a wonderful moment,” Mr. Tompkins, president of the Times Square Alliance, said.“It’s always a historical moment.”

They will share that moment with Mayor Bloomberg and several special guests on a “countdown”stage on Duffy Island, on the north side of the iconic 325-foot building. They will share that moment, too, with a million people who are expected to gather in Times Square to mark the arrival of 2006.

And they will share the moment with 120 million Americans watching the event on their television screens, and with another 1 billion people in practically each of the world’s 191 countries who will see TV images broadcast by free live feeds organized by Messrs. Straus and Tompkins.

That’s some moment.

“Yes,” Mr. Straus said. “It’s a moving moment — especially when you realize that one has played some sort of a role in such a unique celebration.”

The new year will have scarcely arrived when he and Mr. Tompkins start planning yet another moment — to usher in 2007. That means raising $3 million from corporate sponsors such as Panasonic, Coca-Cola, General Motors, MSN, Korbel Champagne, Philips North America, and Waterford Crystal.

It means working with 20 different city agencies on matters such as pedestrian traffic, street permits, crowd control, security, and cleaning up after the party’s over.

It’s arguably the world’s biggest annual party, although London, citing crowds that assemble in Trafalgar Square and Piccadilly Circus on December 31, might dispute that. Paris, too, might join that challenge, noting that New Year’s Eve festivities along the Champs-Elysées could well hold their own against the traditional boisterousness of Times Square.

But neither city is likely to have anyone like Messrs. Straus and Tompkins. Their collaboration underscores how partnerships between the private and public sectors can be commercially advantageous for urban communities.

With his MBA from Wharton, Mr. Tompkins is a natural fit for engendering better commerce for the 5,000 businesses that are peppered throughout his constituency — the area encompassing 40th to 53rd streets between Sixth and Eighth avenues. Also part of his constituency is “Restaurant Row,” the bustling block on West 46th Street between Eighth and Ninth avenues.

Through property assessments, these businesses contribute to the annual $10 million budget of the Times Square Alliance, which Mr. Tompkins has headed for the past three years. Their revenues are driven by the 33 million tourists who traverse Times Square each year, accounting for 80% of the tourists who come to New York annually.

Technically, Mr. Tompkins’ constituency is known as a “business improvement district.” Of the city’s 50 BIDs, Times Square is the third largest in size, after the Downtown Alliance and the Grand Central Partnership.

So when he isn’t meeting with the area’s businessmen and with Mr. Straus, how does he spend his time?

“Working,”Mr.Tompkins said,firmly.

That work involves tending to the redesign of Duffy Square and developing better ways to manage pedestrian and vehicular traffic. It involves planning for new underground facilities to house the additional broadcast equipment that’s installed for coverage of the New Year’s Eve celebrations.And it involves attempting to ensure smoother coordination among city agencies that participate in the creation and maintenance of Times Square’s well-being.

“The biggest challenge is to stay focused on the concept of Times Square as a complex public space — not just an intersection for streets, or a performance center, or a massive broadcasting booth, or as a place to watch electronic billboards,” Mr. Tompkins said.

The billboards festooning One Times Square are certainly a financial boon for the building’s owner, the realty firm Jamestown, with some signs costing several million dollars in leasing fees. The firm bought the building from Lehman Brothers in 1997 for more than $100 million, some $75 million more than what the investment bank paid for One Times Square when it acquired it in 1995.

Mr. Straus, a graduate of Haverford College and the Emory University School of Law, was associated with Lehman Brothers at the time.With the blessings of the 155-year-old firm, he launched Countdown Entertainment.

“The idea was to enhance the euphoria of the ‘Moment’ by developing better marketing strategies,” Mr. Straus said.

Among other things, that meant setting up the event’s own video feed for networks such as NBC, Fox, and ESPN.

It meant, perhaps most importantly, increasing the event’s budget to $3 million from $100,000. Mr. Straus — along with Mr. Tompkins — accomplished that by creating new ways to integrate sponsorships into the event.

And what, besides his anxiety tomorrow night, will Mr. Straus be experiencing as the million-dollar Waterford ball slides down its pole?

“Total delight,” he said. “And the realization that this event will be around long after I am gone.”