Organizers of a rock festival scheduled for Independence Day weekend in Oxford announced more acts for the lineup Friday, including a Frank Zappa tribute band and a group with former members of the Jefferson Airplane/Starship.

But it’s the headlining act, Furthur, that has music fans buzzing about the Nateva Music & Camping Festival, scheduled July 2-4 at the Oxford Fairgrounds.

”You have to hire someone who is going to motivate people to come out, and we think we’ve got that with our headliners,” said Frank Chandler, the festival’s chief executive officer. ”The fact is, the population center of Maine isn’t that dense. and the population centers are a ways away. You’ve got to give them something worth their time and money.”

Anchored by former Grateful Dead members Bob Weir and Phil Lesh, Furthur has been packing concert venues since it began touring in January.

The premise of Furthur is to take the music of the Dead to a different plane, to experiment with the structure of the songs to allow even more room for improvisation.

That theme runs through the rest of the lineup announced so far for Nateva. In addition to Furthur, they include moe., headlining on July 2, and the Flaming Lips, the featured band for July 3. Furthur will play on July 4.

Also on the bill are Zappa Plays Zappa, the music of Frank Zappa played by a band led by his son, Dweezil; Keller Williams, a ”one-man band” who blends everything from folk and bluegrass to alternative rock and jazz; Moonalice, featuring former members of the Jefferson Airplane and its offshoot, the Jefferson Starship; Lotus, an instrumental alt-rock band from Indiana; and a blues/jam band led by Derek Trucks and his wife, Susan Tedeschi.

Chandler hopes to draw 15,000 fans to the festival each day, mostly from across northern New England. He will hold the festival at a 100-acre site at the fairgrounds in Oxford, north of Portland and close to Lewiston-Auburn.

The key to the festival’s success, he said, is hiring bands that will make people want to buy tickets. He thinks Furthur will. If a sold-out show Thursday at the Verizon Wireless Center in Manchester, N.H., was any indication, ticket buyers won’t be disappointed when Furthur rolls into Maine.

Joined by an all-star band of collaborators and minstrels, Lesh and Weir spun off an evening of music that felt fresh, alive and still refreshingly organic, if at times a little long in the jams.

Festivities began at 8, and the party ended sometime before midnight, with one very long set break.

Fans may complain that Furthur is a shell of the Grateful Dead, and that it’s unfair to represent its music as the music of the Dead. Fair enough, but minus the presence of Jerry Garcia, Furthur is the closest we’re going to get to the Dead.

Many of the songs that constituted the staple of Dead shows for decades were there: ”Sugaree,” ”Truckin’,” ”Deal” and a mesmerizing show-closing blend of ”Scarlet Begonias,” ”Fire on the Mountain” and ”Sugar Magnolia.”

The second set provided a classic near-Dead experience — a seamless set of music with barely any breaks between songs, the musicians handing off their parts to others one by one, then rising up together to bring the jam to culmination.

John Kadlecik, who played guitar in the Dark Star Orchestra, handles the parts sung by Garcia, who died in 1995. (Kadlecik is somewhat affectionately known among Deadheads as ”DSO Jerry” for his striking musical resemblances to Garcia.)

In this musical incarnation, Weir and Lesh have turned over substantial responsibility to Kadlecik. He handles many of the vocals, and stepped up to trade jams with Weir on ”Deep Elem Blues” and ”Bird Song.” Otherwise, Weir tackled the rest of the vocal duties.

As an encore, Furthur tapped the influence of The Band, presenting a faithful retelling of ”The Weight.” Curiously, Thursday’s show was among the very few Furthur has played that’s been absent a Bob Dylan song.

The band also includes longtime Weir collaborators Jeff Chiamenti and Jay Lane on keys and drums, respectively. They play with Weir in RatDog. Joe Russo is on drums.