LIMB OBSERVATIONS OF HE-I-1083-NM

Imaging spectroscopic data of the He I 1083 nm limb emission were take n on several dates in October and November 1995 with the NASA/NSO spec tromagnetograph at the NSO/Kitt Peak vacuum telescope and on 9 Decembe r, 1993 with the Michigan infrared camera at the NSO/Sacramento Peak v acuum tower telescope. Emission line profiles were observed in quiet-S un and coronal hole locations on the northern and southern solar poles and on the east solar limb. The height of the He I 1083 nm shell abov e the continuum limb at 1083 nm was measured to be 2.11 +/- 0.12 Mm wi th the Kitt Peak data, and 1.74 +/- 0.05 Mm with the Sacramento Peak d ata. The Kitt Peak data show (1) within the measurement error there is no significant difference in the height or thickness of the emission shell in coronal holes compared with the quiet Sun, (2) the 1083 nm em ission intensity drops by 50% in coronal holes, (3) the line width dec reases by about 2 km s(-1) in coronal holes (suggesting less inclined spicules), (4) the line width of the HeI 1083 nm line jumps significan tly as the line of sight crosses the solar limb (consistent with a hig her temperature upper shell), (5) a quiescent prominence shows a small er spectral line width (consistent with a cooler temperature or less v elocity broadening), and (6) the entire emission shell and the promine nce show a He I spectral component ratio of about 8 (suggesting optica lly thin emission).