Huge searchlights probed the night skies over New York's Lincoln Center Monday night while musicians played brass instruments from adjacent balconies. There was even a bright chandelier shining in the still-darkened Metropolitan Opera House.

It was one of the splashiest benefit galas anywhere -- all to say "hail and farewell" to Beverly Sills.

The event was the absolutely positively final farewell to opera -- not to all singing -- for the star whom the program called "America's most beloved singer." But she did not bid farewell to management either, for she has become the chief executive of the New York City Opera.

And you will be able to see it all on television on Jan. 5, taped, thanks to the Exxon Corp.

The evening was in three acts. There were the pre-performance cocktail parties on a lavish scale; the multitude of performers on stage for the masked ball that is the second act of Johann Strauss' "Die Fledermaus"; and, for the finale, the hugh bash in Lincoln Center.

The early evening parties were in the foyers of the New York State Theater and Avery Fisher Hall. Where you ate and drank depended on how much you paid for your ticket. With Murjani International (that's Gloria Vanderbilt jeans) paying the tab for the whole party, Sills' New York City Opera Company cleared a million dollars or more from the evening (tickets ranged up to $1,000).

The fashion parade included Lady Bird Johnson with designer Molly Parnis, and Joan Fontaine with Pauline Trigere and Adele Simpson. Joan Mondale was there from the beginning.

The heart of the gala was the entertainment, starting with the beginning of the second act of "Die Fledermaus," the opera in which Sills made her debut with the New York City Opera 25 years ago. But the beginning of the second act was as far as the opera went. Not long after Kitty Carlisle, giving a marvelous portrayal of the Prince Orlofsky, had begun to host the famous party, Sills made her entrance as Rosalinda. Soon after that, with the stage filled with her young colleagues, a loud and familiar voice came from the top of the stairway at the back of the stage.

"Beverly! Beverly! Where are you? I know you are here somewhere." It was Carol Burnett, Sills' partner in one of the great TV comedy teams in recent times.

Going from singer to singer, Burnett peered into faces asking each one, "Are you Beverly?" and getting a shake of the head for an answer. When she came to Carlisle, she barked, "What's this ?" To which the prince answered in a deep voice, "And what's this ?" Finally she found Sills, took off Rosalinda's mask, and from there on it was all sheer fun.

"Fledermaus" was over.In its place a procession of Sills' friends paraded across the stage. Eileen Farrell sang "I've Got the World on a String." Ethel Merman brought down the house with "There's No Business Like Show Business," and Mary Martin topped that with the song that is forever hers, "My Heart Belongs to Daddy." Sherrill Milnes did a heart-stopping "Maria," from "West Side Story," and Leontyne Price finished off "What I Did for Love" with a high soft note that spun in the air.

When it was Renata Scotto's turn, she made magic out of what some people may have thought was the exclusive property of Judy Garland as she sang, "Somewhere Over the Rainbow."

Donald Gramm, writing his own text, finished Victor Herbert's famous song as he sang, "She Wants What She Wants When She Wants It," ending, "She gets what she wants when she wants it!"

Then there was Bobby Short to play and sing "Nashville Nightingale," and Jimmy Galway, piping his way down the staircase with a piccolo which he then exchanged for his golden flute as he walked over to Sills, sitting at the side of the stage, and played "Danny Boy."

Heather Watts and Peter Martins danced a lovely pas de deux, and Cynthia Gregory's solo was a dream. John Alexander and Dinah Shore sang, and Placido Domingo poured vocal gold all over "Granada."

Some who chose not to sing appeared on the stage to dance. Sills suddenly found herself waltzing with Walter Cronkite. Others joining the celebration were New York Mayor Edward Koch, Gov. Hugh Carey, Helen Hayes, New York Philharmonic conductor Zubin Metha and Burt Reynolds.

At the end, after one of the brilliant Burnett-Sills comedy routines, it was almost over -- almost, but not quite.

Finally, Sills came out alone on the state, where she was joined by Charles Wadsworth, for many years her pianist. "It has been a long love affair," she told the audience, "and I want to end it as I have so many of my recitals, by singing you an old Portuguese folk song." And if Sills sang the familiar encore without a trace of a tear, there were those in the big house whose eyes were not dry.

Still the night was young. A big blue and white striped tend had been built in Damrosch Park, just beyond the State Theater. There, hundreds of Sills' friends gathered for more partying and to take pictures of her, gathering photographs for hours.

And now the 51-year-old Sills says, "It is over. The comedy is ended. It is done, done, done." But she is speaking only of Beverly Sills, the star of opera and concert. Sills, the manager of one of the world's busiest opera companies, was at her desk for business yesterday. And you may still hear her from time to time on television, certainly next Jan. 5.