These are 5 position alpha-numeric codes comprising the d series. All other level II codes and descriptors are approved and maintained jointly by the alpha-numeric editorial panel (consisting of CMS, the Health Insurance Association of America, and the Blue Cross and Blue Shield Association).
Alaska: Although Alaska enjoys a high volume of aurora activity, its cruises are not often mentioned as northern lights cruises. During the Alaska cruise season, it's rarely dark enough for the lights to be visible.
... that if conditions are just right, you can see the aurora borealis here in Minnesota? Although the northern lights are normally only visible at very high latitudes in places like Alaska and Canada, on extremely active days the auroral oval expands to more southern latitudes.