Selecting points on Earth with fixed solar and spacecraft zenith angles, the FUV brightness is shown below in all three channels. SI-12 was not shown in the movie of the previous page, but varies similarly to SI-13 and WIC, and is plotted below as well.
In each panel is shown the variation in X-Rays (dashed line) as
well as the variation in FUV brightness in a fixed range of solar and spacecraft
zenith angles, the average of which is shown in the upper-right portion
of each panel. Panel A shows the variation of LBH brightness measured by
WIC. Panel B shows the variation in the OI 135.6-nm emission. Panel C shows
the variability in emissions detected by SI-12, which are believed to be
due to NI at 120.0-nm, not geocoronal H Lyman Alpha. Our reasons for this
conclusion for this are stated shortly.
Some important points:
The cross correlation coefficient (r) of the variation in brightness between any of the 3 emissions is .88 < r < .96
The time of peak brightness in all three channels is 10:30 UT, 6-8 minutes after the peak in x-rays observed by GOES.
All three emissions are due to photoelectron excitation, though the NI 120.0-nm emission is primarily through dissociative excitiation of N2