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.
Two major challenges when hunting the Northern Lights are the cold and fatigue. Watching them in a hot spring asolleviates both. The city of Fairbanks, in Alaska, is often cited as the best place to see the Northern Lights in the United States. It's home to the Geophysical Institute at the University of Alaska, Fairbanks, which issues forecasts on Aurora viewing conditions.