Previously flown satellite imaging experiments have demonstrated the suitability of the VUV region for remote sensing observations of auroral particle precipitation. In the wavelength region 120 to 145 nm, a downward-viewing imager is uncontaminated by Earth albedo, and in most cases the intensity of auroral emissions is competitive with rescattered light even during daylit conditions. These features permit quantitative imaging of auroral regions during day and night conditions. An instrument was designed that has adequate wavelength resolution to separate key spectral features and simultaneously observe the Doppler profile of the auroral Lyman-or line. This instrument consists of an F3.8 Rowland circle spectrograph with a far-UV intensified COD at the focal plane. The spectrograph produces a 2-D spectral image where one dimension represents luminosity distribution and the other wavelength dependence. The UV intensified COD is programmed to pick up the luminosity distribution of various key spectral regions. The entrance slit is parallel to the spin axis and during rotation, a complete luminosity map of the region under the satellite is recorded. The proton velocity distribution will be studied by Doppler profile measurement of the Lyman-α line. A Hadamard grille is superimposed on the spectral slit and the Lyman-α data are deconvolved to obtain the required wavelength resolution.
Stephen B. Mende,
Stephen A. Fuselier,
"Ultraviolet imaging spectrometer for monitoring high-latitude precipitating patterns," Optical Engineering 32(12), (1 December 1993). http://dx.doi.org/10.1117/12.155601