Question for you snow experts: are rainbow sparkles common?

6 seconds, ISO-2500, f/3.5 with a Canon 10-22mm wide angle lens on a Canon 7D

Depending on how bright the lights are, I might go up to 8 seconds or down to ISO-1200. I prefer the shorter exposure though, to keep the stars crisp and not blur the lights too much. That night (pictured above) the lights were moving fast so I reduced the exposure and upped the ISO (light sensitivity) in an effort to keep some definition to the aurora.