The extreme ultraviolet spectrum of the sun

Abstract

The present state of knowledge of the spectrum of the sun from 3000 ~ to 170 A. is critically reviewed. The characteristics of the different photographic and photoelectric spectroscopic instruments and the results are summarized and compared. Topics covered are line identifications, intensities, the continuum and its origin, the sun's surface in Lyman alpha, the profiles of H and K of Mg II, Lyman alpha and beta, and monitoring work conducted from rockets and satellites, including OSO-I.

Space observations of the variability of solar irradiance in the near and far ultraviolet

“…there is good agreement with the NRL rocket data (Tousey, 1963) and the absorption cross section, cr = 1.44 x 10-17 cm 2 (Watanabe, et al, 1953).…”

“…The double monochromator had a spectral band pass of 10A and a triangular slit function. A comparison of these Nimbus measurements with a revision of the NRL data by Thekaekara (1970), that of Neckel (1968, 1970), Makarova andKharitonov (1969), andTousey (1963) is shown in Figure 3. In this figure the values of solar irradiance are integrated over 100A intervals except for the measurements with the BUV experiment and the values listed by Labs and Neckels (1968) beyond 3275A.…”

“…The basic limitation on the accuracy of the measurements of solar irradiance contained in Table 3 is the accuracy of the standard of spectral irradiance. 1) 1027-1775A (Hinteregger, et al, 1964) 2) 1800-2600A (Detwiler, et al, 1961) 3) 2600-4000A (Tousey, 1963) The sensor response at a given wavelength, X, is given as the sum from 0 to X of the product of the filter transmission, photocathode quantum efficiency, and the solar irradiance. These functions are.…”

“…Hinteregger, et al, 1964, Detwiler, et al, 1961and Tousey, 1963 Signals calculated using H Ly a flux of Timothy and Timothy (1970), other emission lines from Hinteregger, et al, 1964, and solar continuum at 4500 K.…”

“…The sensitivity curves (product of filter transmittance and photocathode quantum efficiency for sensors A-C) are shown in Figure 1 with Thekaekara (1970), Neckel (1968, 1970), Makarova andKharitonov (1969), andTousey (1963) The wavelength selectivity of a sensor is produced by using a suitable radiation resistant optical filter (Heath and Sacher, 1966) Measurements of the solar irradiance at 12 discrete wavelengths from 2550-3400A with a 10A band pass are being made with a tandem Ebert-Fastie type double monochromator on Nimbus 4 (BUV experiment). In the latter experiment the monochromator views a solar illuminated diffuser plate.…”