Recordings from the Mayall Telescope, which is a four-meter (158 inches) reflector located at the Kitt Peak National Observatory, as well as the Hall 42-inch (1.1-meter) fork-mounted telescope at Lowell' Observatory’s Anderson Mesa dark-sky site, which has been a workhorse telescope for more than half a century. Of the two I found the smaller one more interesting - its motor drive (now obscured by cooling fan noise) is an exquisitely fascinating sonic melange, while the dome booms and squeals are out of this world.
You can hear how I used these sounds in my immersive audio documentary Lonely Nights (BBC Radio 4) here: https://soundcloud.com/diane-hope/lonely-nights-bbc-r4
