Radiation astronomy/Telescopes

The Nordic Optical Telescope (NOT) telescope buildings at Roque de los Muchachos Observatory is shown in June 2001. The height (2396 m) of the observatory above the Atlantic Ocean ensures that it is almost always above the clouds.

The building of the Nordic Optical Telescope is shown near the time of sunset. Credit: Bob Tubbs.
The interior of the telescope shows an instrument on the Cassegrain focus. Credit: Nordic Optical Telescope/Craig Mackay.
This is Saturn imaged with the Stockholm Infrared Camera (SIRCA) in the H2O band. Credit: M. Gålfalk, G. Olofsson and H.-G. Florén, Nordic Optical Telescope.{{fairuse}}

At left is the LuckyCam instrument attached to the Cassegrain focus of the Nordic Optical Telescope.

At the second down right is Saturn imaged by the Stockholm Infrared Camera (SIRCA) in the H2O infrared band to show the presence of water vapor. The image is cut off near the top due to the presence of Saturn's rings.

The Sun's emission in the lowest UV bands, the UVA, UVB, and UVC bands, are of interest, as these are the UV bands commonly encountered from artificial sources on Earth. The shorter bands of UVC, as well as even more energetic radiation as produced by the Sun, generate the ozone in the ozone layer when single oxygen atoms produced by UV photolysis of dioxygen react with more dioxygen. The ozone layer is especially important in blocking UVB and part of UVC, since the shortest wavelengths of UVC (and those even shorter) are blocked by ordinary air.