This directory contains Extrem Ultraviolet (EUV) reference spectra and 
related EUV model parameters based on the measurements and work of H.E. 
Hinteregger and his colleagues. The model and reference spectra (R74113, 
F74113, F76REF, SC21REFW) are described by Hinteregger et al. (Geophys. Res.
Lett. 8, 1147, 1981). The spectra and model are based on rocket measurements 
and simultaneously obtained EUV fluxes by the AE-C and AE-E spectrometer. 
The rocket measurements were used to establish absolute calibration factors 
for the AE-E instrument. The originally proposed R74113 spectrum (Hinteregger,
J. Atmos. Terr. Phys. 38, 701, 1976) is based on AE-C measurements and data
froma rocket flight on April 23, 1974. R74113 revised to become F74113 
(Heroux and Hinteregger, J. Geophys. Res. 83, 5305, 1978), following refined 
evaluation of the rocket and satellite data. F76REF used in addition AE-E 
data from July 13-28, 1976 (when solar activity was low and constant). 
SC21REFW extends F76REF to include a rocket flight on August 14, 1979.
The F76REF and SC21REFW files include also the wave-length dependent 
adjustment factors that are used in Hinteregger's flux model.