Star Trails in Daytime?

This shot was taken at -- believe it or not -- 9:00 PM on March 15, 1997;
sunset was at 6:40 PM. A seven-day old first-quarter moon (51% illuminated)
provided the "sunshine" required for this shot. This was a 10-minute exposure
at f/4 on a tripod-mounted 35mm camera. Note the star trails in the sky and
the lack of observers at the telescopes (with the exception of the observer
at the refractor to the right of the silver tent). No one stood still long enough
to be captured on film; only a few red flashlight trails show that people were
indeed moving around at the site. For instance, the red trails at the far right
were from me, setting up my 6" Newtonian reflector on the pad.