[dr_lew]

Probably a short time exposure for the stars, and then a flash exposure of the arch, with the same camera setting.

[dr_lew]

Here's a clip from the photo matched with my Starry Night view from a Utah location ( Salt Lake City - close enough for this purpose )

The "red" star is Antares in Scorpio. The red lines in the star chart are hour lines and latitude lines. The hour lines are 30 minutes apart here, so you can see the exposure was maybe a minute or tow long to produce the trails that we see. ( I can get a better estimate by blowing up the scale. )