The figure is the "first light" spectrum of the UVCS/Soho
Lyman-alpha channel. The observation is a 40 arcminute
strip of the corona parallel to the east limb tangent
and centered at about 3
solar radii from sun-center. The spectral line is
HI Lyman-alpha at a wavelength of 121.6 nanometers. The
brightest part is from a streamer
that is also being observed by the LASCO instrument.
The background demonstrates the low dark
rate and stray light of the instrument--fewer
than 10 counts per second shared by 360,000 picture
elements.