Actually Jerry,
That's not quite correct. The star trails are affected very much so by reciprocity failure. Tests that I did a long while ago with hypered Kodak PPF400 and well as Ektachrome in a cold camera showed that reduced reciprocity failure greatly increases the number of stars you see in a star trail photo. By reducing reciprocity failure, you end up with better contrast in the image between the stars and skyglow. Of course, what many people do to avoid the skyglow issue altogether (as it is a problem for both film and digital users) is to take multiple exposures of say 15 minutes each. That way sky glow is avoided, and the digital sensor will dig deeper than film possibly can and you keep the nice star trail effect.
Believe me, after doing this for more than 25 years, I've got a pretty good handle on the limitations for film in astronomical imaging. Star trail shots are an extremly testing type of photography for both film and digital. As most shots are much shorter in duration, I will reitterate that film holds no advantages here....including resolution.
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