Exercice 2 : Détection des points chauds et des panaches   Thermal hot spots are seen as bright pixels in the summit area of Etna in band 21 and 22 of the MODIS image from 24 July 2001. Data in the range of ~4µm (3.929 - 3.989µm) was recorded in both bands, and is the most suitable for hot spot detection.