Measurements with an auroral spectrometer in the Energy Budget Campaign

A combination of grating spectrometers and photometers with 18 detectors was started twice during the Energy Budget Campaign from Kiruna, Sweden. The optical design of the instrument is described. The extensive calibration requires different techniques for the wavelength ranges from the extreme UV to the visible part of the spectrum. In order to determine the photon fluxes generated by precipitating particles during auroral events, the experiment completely covers the spectral region from 50 to 650 nm, some wavelength channels overlapping. The spectral resolution for the instrument part scanning the shorter wavelengths (50 to 250 nm) is 1 nm and for the other instrument part (105 to 650 nm) is 3 nm. Up to 14 spectra are recorded in each of the wavelength channels for different height regions above 100 km. At the same time, monochromators at 83.4, 98.9, 120.0, and 215 nm and photometers at 130.4, 337.1, 391.4 and 557.7 nm record auroral emissions from ionized and neutral atomic oxygen and molecular nitrogen.