The 3.7-µm channel (comparable to the 3.9-µm channel on GOES) is more sensitive to hot spots (fires, volcanoes, etc.) than the 11-µm channel. Notice how quickly the fire expands and gets hotter with time. The hottest temperatures associated with the fire are indicated by the yellow, orange, and red pixels, with the red being the hottest. At the time of the images, the fire was reported to cover approximately 20 square kilometers. By 18:18 UTC several very hot pixels show up as red in the enhancement. The 3.7-µm channel is used for fire detection and monitoring over Alaska as well as other regions over North America.