SKYLAB observations of H I Lyman-alpha

The H I Lyman-alpha profiles obtained with the Skylab SO82-B spectrograph at spectral and spatial resolutions of 60 mA and 2 arcsec x 60 arcsec are presented. Profile variations are illustrated from center to limb, at different heights above the limb, and over a cell and network boundary. The Lyman-alpha core exhibits weak or no limb darkening, whereas the line wings show weak limb darkening. Above the limb, the Lyman-alpha core integrated intensity and line width remain in essence constant up to plus 12 arcsec and may result from resonance scattering of chromospheric radiation by coronal neutral hydrogen or from spicules. On the disk, intensities in the line core are seen as correlating well with the H-alpha network; however, the Lyman-alpha wing intensities are found to correlate better with the transition region lines. The average of profiles acquired over the cell and network region is found to be similar to profiles obtained in the cell.