The AirGlow Applet shows the observed spectrum of the night sky. It is a composite of two spectra taken by R.Napiwotzki with the 3.5 m telescope at the German-Spanish Observatory on the Calar Alto mountain. These spectra were taken to determine the sky background which has always to be subtracted from the proper spectra of astronomical objects.

The two spectra were joined together at 5544 A. Towards the lower and upper wavelength end, the continuum level rises because the intensity calibration becomes inaccurate.

The spectrum contains many emission lines from atoms and molecules that are excited by various processes.

Enter the minimum and maximum wavelengths (in Angstroem) of the region to be displayed, then press the Show-Button. The vertical axis shows the (linear) intensity, and is always scaled to the maximum value in that region.

Clicking the Mouse will display the wavelength of the position of the mouse.