From Robert Schwarz…
24h star trails from Robert Schwarz on Vimeo.
This was a test run for a 24h star trail shot, only possible close to either Poles ;)
The camera was out from midnight 17 May 2015 until midnight 18 May 2015. Look at the streaks about half way from horizon to zenith, this are Iridium satellites, each flare nearly 10 min apart.