Søndag is Norwegian for Sunday, and Rune Lindbæk’s Sunday is the 3 a.m. carryover from Saturday night: still driven by the fading impulse to move, but accommodating the feeling of wanting something to propel you on the journey home from the club. It’s also something of a carryover from some late ’90s leftfield/downtempo/acid jazz inclinations that Lindbæk showed during his time as a co-producer in the Those Norwegians/Drum Island collective — a refinement of tendencies that he’d arrived at through a near-decade-long circuitous route through hardcore techno (Open Skies) and diva house (Volcano). Account for that, then throw in a few big beat/trip-hop maneuvers — the spacey sleazy-listening boom-bap of opener “Ok, Kjør Romskip”; the rubbery bloop-funk of “Fotihusedit”; the bleary-eared closer “Søndags Beste” (which samples both Ryo Kawasaki’s cult-classic fusion gem “Bamboo Child” and the radio play of The Hitchhiker’s Guide to the Galaxy) — and Søndag feels like the early vanguard of a sound that seems half-formed but on the verge of becoming definitive of something. And that something was the space disco sound that former collaborators like Bjørn Torske and Röyksopp’s Torbjørn Brundtland were arriving at around the same time: almost preposterously smooth, blissfully relaxed in Balearic tradition, but still driven by the kind of bass-first warmth and buoyant hip-swivel energy that made for lighthearted yet sure-footed disco reclamations. The yacht-fusion glide of “Sin Zen” and the synths-and-strings boogie-down jam “Junta Jæger” are musts for anyone who caught on to space disco by the turn of the ’10s, but still hold some curiosity over what its early phase sounded like at the turn of the millennium.