"Uptown," a muscial tribute to Harlem's illustrious Apollo Theater, lights up the air like a skyrocket tonight on Nbc, but this particular skyrocket has been languishing in drydock for over a year while network executives delayed its broadcast. Considering all the dreadfulness NBC has perpetrated in the interim, the delay seems especially clumsy.

Maybe they thought the special was just so recklessly entertaining it would produce mass culture shock. 'or maybe, just maybe, it was feared that a program featuring mostly black performers would not attract sufficient millions of white as well as black viewers. That's ridiculous. The show, at 9 tonight on Channel 4, is an exuberant celeration of true Americana produced beautifully by Gary Smith and Dwight Hemion.

The Apollo was a cultural landmark from the '30s through the '60s, and legends like Fats Waller, Bessie Smith, Ella Fitzgerald, Ray Charles and innumerable others made it the epicenter of, among other things, the urban blues.

Fittingly enough, the program -- tapd early last year in Hollywood -- opens and closes on notes of electrifying elation. Cab Calloway and a chorus bring the house down first thing with a medley that includes Duke Ellington's immortal "Take the A Train," and the show closes with the entire cast joining the Mighty Clouds of Joy for a pop-gospel rouser.

It could well be said that the performers of today chosen to salute those of yesterday are not completely satisfying surrogates. And yet Lou Rawls, Natalie Cole and Gladys Knight perform at a level beyond their usual limits -- especially Cole, whose voice remains thin and shallow. Sarah Vaughan and Billy Eckstine exchange come-hither ballads during an interlude radiant with pizazz.

The Temptations elegantly navigate a medley saluting groups like The Mills Brothers, The Ink Spots, The Coasters, The Platters, The Drifters, and Themselves. Flip Wilson and Nipsy Russell re-create, not too fluidly a vintage comedy routine. And Calloway presides over a spectacular, brief remembrance of the Apoolo's neighbor, the Cotton Club, where white audiences were able to partake of the Harlem Renaissance.

Some may find the music overly homogenized, but there is a faithful essence to most of the numbers and a heartfelt authenticity to others. It's a pity there weren't more old film clips and that those used have been abruptly edited; Fats Waller is just about waist-deep in "Aint Misbehavin" when he fades maddeningly away.

Otherwise, Hemion directed in his usual masterly way, Harry Crane and Marty Farrell wrote the serviceable continulty (with Jack Albertson as Frank Schiffman, who first managed and later owned the Apollo), and Tom H. John's art direction once again proves glitteringly impeccable.

This is a program that goes from bombastic and grandiose pleasures to sweet and delicate ones, almost all of them royally evocative. Doc Severinsen, whose whiteness did not by any means keep him from playing in a band at the Apollo years ago, wails through a tribute to Louis Armstrong, and Rawls, electronically cloned into three of himself, does a very presentable Ellington medley.

But what may be considered the quiet highlight is provided by venerable hoofers Sandman Sims and Bunny Briggs (featured recently in the PBS "Non Fiction Television" program "No Maps in My Taps"), both uncommonly fluent in that jargon of the gods, tap dancing. Briggs beaming through a chrous or two of "My Shining Hour" is an uncompromised act of magic -- one more sterling turn that makes "Uptown" two shining hours indeed.