A raw image from ISAAC

This raw ISAAC image was used, combined with many others, to generate the photo at the top of this page. All the images taken with astronomical instruments are monochromatic: the information on the colour is obtained by taking exposures through different filters. In infrared light, the sky is so bright that individual exposures must be kept very short. To reach the long total exposure time needed, hundred of exposures are combined. The dark spots are defects of the detector, and the bright line in the centre marks the separation between the areas of the detector processed by different electronics.