The lights, emanating from searchlights on rooftops on the south side of the Parkway and on ground level along Pennsylvania Avenue to the north - a Best Western hotel there did not allow searchlights on its roof - took center stage from a crescent moon in the clear sky.
Necks craned skyward and the crowd of several thousand oohed and ahhed as the lights switched on about 9, creating an angular web of intersecting beams, collapsing and expanding, narrowing and spreading, its apex 600 feet high and moving across the sky.
It was a bit like a giant string game of cat's cradle - "a cool mixture of visual and audio art," said onlooker Brian Bonanni, 30.
It was also, for some, maybe a bit more subtle than they expected, as the lights flickered maturely and elegantly to the screeching and beatboxing of Moss and Rahzel. "I'm waiting for the rave," said Rebecca Canna, 38, of West Philadelphia.
And, naturally, there were glitches. When it came time to go to the website for the recordings, Lozano-Hemmer was unable to load them to project onto the Parkway through speakers. He turned the lights off to try to fix the problem, then turned them back on - without sound. "When things crash, you see them [artists] sweat," he said. Dress rehearsal!
All evening, streetlights along the Parkway's inner drive were turned off, making an unusually dark run-up to the light spectacle, as a mostly young crowd lined up at food trucks waiting for the show to begin.
Lozano-Hemmer, based in Montreal, has compared Open Air to a light installation he did in Mexico City's central square in 1999 in which 800,000 people participated.
The Philadelphia project runs nightly from 8 to 11 p.m. through Oct. 14. Commissioned by the Association for Public Art, it is part of the almost-over Live Arts Festival (and forthcoming DesignPhiladelphia) but was delayed by Jay-Z's Made in America festival on the Parkway on Labor Day weekend.
In the hundreds of snippets recorded in the run-up to the debut, Philadelphians proved themselves to be a, um, slightly eccentric crowd.
"My mother pickled cucumbers in Mason jars," Bonnie MacAllister of Oxford Circle recalls in one.
"Jacque" reads a "quirky poem" that is actually quite dark, about two dead boys and a deaf policeman.
There was a recording of Harry Kalas, though surely on Thursday night, with a wild card spot still on the line, Harry was looking down on the Phillies-Mets game, not the lights over the Parkway.
There was the Friends Select School choir singing "Imagine," and Zoe Strauss ruminating on how she selects subjects to photograph.
In the queue online, Jonathan Cresson received a relatively high 86 votes to keep him in the top dozen or so, but only an average of three stars for a boldly screechy rendition of his original composition, "We Love This City, We Love the Lights!"
As Britney Spears might have said, were she judging this talent fest, "The singing came in, and it wasn't very nice."
No birds were seen falling from the sky, as had been feared by Pennsylvania Audubon members who got Lozano-Hemmer to agree to pause the light show at times to allow birds on the migratory superhighway to get through on their way to Cape May and beyond.
There are two basic ways to record a 30-second snippet whose frequency and amplitude will set the 24 robotic search lights into their digitally controlled frenzy.
The iPhone app - Open Air Philly - works when you are on the Parkway. It will bump your message to the top of the queue and direct a searchlight at you via GPS when your spot is in the sky.
The website, www.openairphilly.net, allows you to record, read, listen to and vote on the hundreds of entries. You are notified when your spot is about to be translated into modulating light.
The recordings that correspond to what is actually above the Parkway can be heard on the app, the website, and over speakers at Eakins Oval and the visitor center at 18th Street.
Contact Amy S. Rosenberg at 215-854-2681 or firstname.lastname@example.org. Follow on twitter @amysrosenberg.