David Singer's BG-179 is a poster that has to be read carefully, because it advertises two shows at once. By the summer of 1969 Bill Graham's print runs often folded two consecutive bookings onto a single sheet, and this one covered both: Iron Butterfly, Cold Blood, and Sanpaku for June 24-26, and then a completely different bill - Spirit, Lee Michaels, and Pyewacket - for June 27-29. Thursday, June 26, was the closing night of the first half. The acts on stage that night were Iron Butterfly, Cold Blood, and Sanpaku; the names lower on the poster belonged to the following weekend, and not to this night.

Iron Butterfly arrived at the corner of Market and South Van Ness at the absolute peak of their fame. In-A-Gadda-Da-Vida, the album whose seventeen-minute title track had become a kind of national rite of passage, had been released a year earlier in June 1968 and had not stopped selling since. They were, briefly, one of the biggest heavy-psychedelic acts in America, and the Fillmore West - the old Carousel Ballroom, which Graham had renamed and taken over the previous July - was exactly the room to hold that weight.

Under them were two very local stories. Cold Blood was a brand-new Bill Graham signing, an East Bay horn-driven soul-rock band fronted by the singer Lydia Pense; Graham had reportedly picked them up in 1969 after an audition that Janis Joplin recommended, and their debut album was still months away. Sanpaku, opening, was an obscure Sacramento jazz-rock group with two horn players and a short life - formed in 1968, gone by the end of 1969 - who nonetheless turned up on several Fillmore West bills that year.

The poster matters as much as the music here. BG-179 was only the second design David Singer made for Graham, at the very start of a run that would make him the most prolific artist in the numbered Fillmore series. Victor Moscoso had referred him; Singer answered the wild Wilson-and-Griffin psychedelia with something cooler and stranger - surreal photo-collage, Magritte by way of the airbrush, Art Deco lettering. The look of the late Fillmore West, the one most people picture, starts about here.

No setlist survives for the night, and Iron Butterfly had played the Fillmore West before, so this wasn't a debut of anything except, arguably, Singer's emerging style. It was one night - a Thursday, the last of three - near the top of the bill's brief, enormous moment.