Victor Moscoso's FD-68 is one of the posters that made the Avalon Ballroom look like the Avalon Ballroom - vibrating complementary colors, lettering you have to lean into to read, a piece now held in the permanent collections of both the Museum of Modern Art and the Fine Arts Museums of San Francisco. It advertised a four-night Family Dog run, Thursday June 29 through Sunday July 2, 1967, and like a lot of Moscoso's work it is slightly hard to pin down even at the level of who was on it.

The printed bill names Quicksilver Messenger Service on top, then Mount Rushmore, then Big Brother and the Holding Company - and then a fourth act that the catalogs read two different ways. The poster's own lettering, as the Fine Arts Museums and the Portland Art Museum transcribe it, reads "Horns of Plenty" (a real band that had played the Avalon a few weeks earlier); the Museum of Modern Art's catalog, and the show-list keepers, render the same slot as "Blue Cheer." They are looking at the same Moscoso lettering and reading different words, which is itself a fair description of Moscoso.

What actually happened on opening night is a separate question from what the poster says, and here the night-level record diverges from the print. The most careful reconstruction of Quicksilver's bookings - from the San Francisco Sound researchers - gives the June 29-30 nights as Quicksilver, Mount Rushmore, the short-lived Emerald Tablet (possibly cancelled on the 29th), and the Texas songster Mance Lipscomb, with Big Brother not listed on those first two nights. Janis Joplin and Big Brother are on the poster, and they almost certainly played later in the run; but the documentation for opening night doesn't put them on the Avalon stage on the 29th, so this page won't either. What it will say with confidence is the part every source shares: Quicksilver Messenger Service headlined, and Mount Rushmore was there.

That's the honest version of a famous poster - the art is canonical and museum-held, the headliner is solid, and the supporting cast is a genuine tangle the surviving records only partly resolve. Thursday, June 29, 1967, opening night at the Avalon: Quicksilver up top, Mount Rushmore under them, and a bill the poster and the logbook describe a little differently.