Reprinted from yesterday's late editions.

Monday was Aaron Copland's 77th birthday. Monday night Mstislav Rostropovich and the National Symphony Orchestra threw him a birthday party in the Kennedy Center Concert Hall.

When Rostropovich first led Copland to the conductor's stand, the audience rose and began the first of several long ovations. Finally Copland raised his hands, and when things quieted down, began to speak.

"Ladies and gentlemen, friends," he opened. "You can well imagine by emotion at this moment. I have never heard of an American composer invited by an entire orchestra to have his birthday celebrated with a whole concert of his music."

There was a lot more applause before Copland could begin the lambent beauty of "Appalachian Spring." Rostropovich opened the concert with the arrangement of "Happy Birthday" that Copland wrote eight years ago for Eugene Ormandy's 70th birthday. And when Copland first came onstage last night, the entire orchestra rose, something Rostropovich had told them only a few weeks ago was an honor to be reserved for great men such as Copland and Bernstein.

When that music ended, with the special hush it always induces, there was aanother tumult of enthusiasm for this man who is at once a folk and an artistic hero.

Rostropovich next led a flaming account of "El Salon Mexico" in a way that suggested he had grown up in Mexico City's Numero Uno hot spot. Yet after Copland returned to lead his Piano Concerto with his friend and colleague Leo Smit, Rostropovich turned with wonderful assistance from the Paul Hill Chorale, to the suite from the opera "The Tender Land," and now it seemed as if the conductor had spent his early days at Kentucky barn dances.

As ushers brought forward two baskets of flowers for Copland, one from the orchestra and one from its conductor, Rostropovich led everyone - chorus, orchestra and audience - in one final chorus of "Happy Birthday, Dear Aaron," which looked as if it left the composer speechless.