AMONG MAJOR composers, who wrote the most operas? Wagner? Verdi? Wrong. Mozart? Puccini? Wrong again.

George Frideric Handel, creator of 44 operas, is the indisputable record holder -- and there would have been even more if audiences in Handel's adopted London had not lost their enthusiasm for opera.

To be sure, not every one of the 44 is a gem, much less a masterpiece, even by the considerably different standards of Handel's day. They do, however, contain some of Handel's finest passages, according to Handel's ardent champion, Stephen Simon, who will open the Kennedy Center's fourth Handel Festival this Saturday night with a performance of the opera, "Radamisto."

Simon, who has been director of the Handel Festival since its inception, believes the performance will be the American premiere of "Radamisto" -- a mere 260 years after its creation -- and the first performance in the original Italian since Handel's death in 1759. (Revivals of recent years in England and Germany were presented in the language of the country.)

In its won time, "Radamisto" was a London his and something of a landmark. Introduced in 1720, it was Handel's first opera for the Royal Academy of Music, an organization under the partonage of George I devoted to the presentation of Italian opera at the King's Theater in Haymarket. Handel had been made its chief composer and director with responsibilitiy for assembling its company if singers as well as its productions.

Having spent several years in Italy, Handel had fully absorbed its operatic style which was the rage throughout Europe and "Radamisto" was undoubtedly the finest example London has thus far heard. Its dramatic mastery also represented a new level of achievement for Handel, who had been writing operas off and on for over a dozen years. Of particular interest was his inventive use of an exceptionally large orchestra for "Radamisto," which employed horns for the first time in English opera pit.

In its orginal form "Radamsisto" is one of Handel's longest operas, "four hours of not always inspired music," according to Simon, whose first task was to put together an edition suitable for today's audiences. "The biggest problem for today's audiences. "The biggest problem was trying to restrain one's self-indulgence, and not be seduced by the lesser material," explained Simon, who pared the opera down to 2 1/2 hours and reduced its three acts to two.

Simon eliminated what he called the "soap opera material -- lots of subplots with extra princes and everybody failing in love with the same girl" and concerntrated on the central story line, which has melodrama aplenty. Based on an excerpt from Book XII of the "Animals" of Tacitus, the plot of "Radamisto" revolves about the king Tiridate's attempt to usurp a neighboring kingdom that belongs to his aging father-in-law, Farasmane. In the process Tiridate alienates his wife, Farasmane's daughter Polissena, and falls in love with Zenobia, the faithful wife of prince Radamisto, son of Farasmane. Rounding out the cast are Fraarte, Tiridate's brother and Tigrane, an ally of Tiridate.

In accordance with the conventions of Handel's time, which decreed that no principal could be killed off (and thus lost vocally), Tiridate, particlarly vital as the only tenor, barely misses being executed; Farasmane is nearly done in several times; Polissena almost dies trying to save her husband, and Zenobia nearly drowns after throwing herself in the river to escape Tiridate. There is a traditional kiss-and-makeup ending in which Tiridate claims to have been temporarily insane and receives forgiveness all around. The principals then close the work with a handsome chorus, the only opera's such vocal ensemble.

Ridiculous as it reads, "Radamisto's" plot was more plausible than many of its day, since it involved family problems solved in human ways. In fact, the genre known as opera seria -- literally, "serious opera" -- to which "Radamisto" belongs was defined by the reality of its story as opposed to operas based on magic and mythology. Continuous dramatic development meant little to Handle's audiences because they were interested above all in the singers; particularly the principals, whose merits were often loudly debated during secondary passages. For the same reason "Radamisto," like other operas of its time , lacks extensive vocal ensembles. If several singers were carrying on simultaneously, audiences felt they could not properly judge individual vocal abilities.

Even if some of "Radamisto's" conventions seem absurd in the light of later operatic developments, the fundamental appeal of its music remains, according to Simon. "There is a tremendous amount of beautiful melodic content," he explained. "Handel was as great a melodist as Schubert. At the end of 'Ombra cara,' for example, I envision the audience as being sbsolutely over-whelmed. It's ravishing -- a real four-handkerchief aria."

'Ombra cara" sung by Radamisto after the supposed death of his wife. It is one of the opera's high points by all estimates, including that of Handel, who deemed it and "Cara sposa" from Rinaldo" his two best arias.

"Radamisto" also contains Zenobia's extraordinary aria, "Empio, perverso cor," in which Handel explores two strongly contrasting emotions. According to the music's directions, Zenobia defies ardito e forte her would-be suitor, Tiridate, while consoling adagio e piano her disguised husband, Radamisto.

The virtuoso singing required for such music draws aficianados of the vocal art today as much as it did in Handel's time, observed Simon. Vocal ensembles are not missed, particularly in "Radamisto," he added, because "within the orchestral fabric there are areas for solo trumpet, flute, violin and horn. You have, in effect, an ensemble between voice and instrument and that creates plenty of variety."

"Radamisto will be followed by the oratorios "Judas Maccabeus" on March 15 and "Samson" on April 19. In December, Simon will return to conduct, Handel's opera, "Semele," in the Terrace Theater as part of the Washington Opera season.

Assessing the future of Handel the opera composer, Simon said: "The one thing that comes through loud and clear is that the Handel operas really presage Mozart -- and not by very much. There is music of great emotional impact and extreme beauty. Assuming the festival goes well and 'Semele' is well received, I can see nothing but good things happening for Handel. And there's certainly plenty of repoertoire."