A Van Morrison live recording from 1968, which has been the subject of fan discussion for years, was briefly released on iTunes without announcement then removed around 24 hours later.

As Stereogum reported, Morrison began developing his trademark post-Them sound during a series of low-key performances in Boston during August of that year, accompanied by a local bassist and flautist. The experiments would shape his groundbreaking second album Astral Weeks.

A recording from one of those appearances, in the city’s Catacombs club, was made but never released, and hadn’t even been available as a bootleg. That changed on Wednesday, when an album titled Live in Boston 1968 appeared on iTunes U.K., with a simple black-text-on-white-background cover image. By Thursday it had been deleted.

Author Ryan H. Walsh, who wrote the book Astral Weeks: A Secret History of 1968 about his search for the recording, responded to its release by tweeting, “This is totally bananas. Today, Van Morrison unceremoniously released the ’68 ‘Catacombs Tapes’ … this is the legendary recording I spend the whole book trying to track down & here… and, uh, now YOU can too!”

He reported that the audio had been “cleaned and boosted” from the version he’d previously managed to track down and that there was an additional track he hadn’t heard before.

“Tom Kielbania (bass) is over the moon about this release," he noted. "This is the only audio proof he had anything to do with any of this… as well as demonstrating that the Boston trio really did develop the acoustic, pastoral sound of Astral Weeks in the weeks before they were replaced by jazz musicians in New York.”

Walsh also suggested a theory about why the 50-year-old album’s release was so limited. “The most sensical interpretation of the terrible cover art and U.K.-digital-only distribution is that this release is a ‘copyright dump,’ i.e. its main function is to preserve Morrison's copyright of the recording (otherwise, come January, it would become public domain)," he explained.

It’s not known whether a full-scale release is set to follow, but Walsh said, “I'd also imagine these files will be on ... all kinds of sites now that they've been officially released.”