"Halcyon" is a song written and performed by Orbital, dedicated to Phil and Paul Hartnoll's mother, who was addicted to the tranquilliser Halcion (Triazolam) for many years.
It was released as Radiccio EP in the UK and Japan, and as Halcyon EP in the US.
The song features two samples from earlier international hit singles. The first sample is a backmasked vocal sample by Kirsty Hawkshaw from "It's a Fine Day" by Opus III (1992). Ed Barton, the composer of "It's a Fine Day", receives a co-writing credit for the track.
The second is a vocal harmonies sample in the song "Leave It" from the 1983 album 90125 by the progressive rock band Yes. There is no co-writing credit for the Yes sample. The beats were produced by a Roland TR-909 rhythm machine.
On Orbital's second eponymous album the track "Halcyon + on + on" appears, a slightly more upbeat and melodic remix of the original song. In contrast to the original, the remix is far more widely known, and has been featured on several movie soundtracks (most notably Mortal Kombat (1995), Hackers, CKY2K and Mean Girls).
The title of the remix is inspired by a contemporary advertising slogan used by the Ariston washing machine company ("Ariston + on + on"). "Halcyon + on + on" is somewhat shorter than the original, at 9 minutes and 27 seconds long.