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Near second and third contact during a solar eclipse the spatial spectrum of the solar illumination changes as the relative power at high spatial frequencies increases strongly. Since groundlevel atmospheric scintillation depends on a weighted integral of the image power spectrum, we can expect to see a measureable time dependence to solar scintillation during an eclipse. This effect was observed during an annular solar eclipse and quantitatively compared with a scintillation model. [ABSTRACT FROM AUTHOR]

Considerable effort and progress has been made in measuring the internal solar rotation from observations of the odd-order helioseismological splitting coefficients (cf. Brown and Morrow, 1987, and references therein). Less progress has been made in using the even coefficients to measure the internal solar structure (cf. Duvall, Harvey, and Pomerantz, 1986; Gough and Taylor, 1984; Dziembowski and Goode, 1984, and references). Yet, small deviations from spherical symmetry in the internal solar structure may be inferred from the helioseismological splitting observations. Spherical-harmonic decomposition and first-order perturbation theory provide a convenient formalism for describing the distortion. Here I describe the formalism and a new, computationally efficient, method for calculating the kernel functions that are needed to invert the splitting data to obtain the structural asphericity. [ABSTRACT FROM AUTHOR]

The Imaging, Tunable Magneto-Optical Filter (ITMOF) is a one- or two-cell magnetic birefringence filter designed to measure the Doppler shift of the solar potassium line (770 nm) with respect to a laboratory standard. Two gas vapor cells contain isotopically refined potassium and operate at temperature near 393 K. Hot cell windows are employed in a carefully controlled thermal environment to limit spurious birefringence in the pyrex cell and prevent condensation in the light path. Electromagnets provide a variable strength and direction longitudinal magnetic field of up to 5000 G on each cell. There is no rotating quarter-wave plate or other moving parts. The final image is detected with a CCD camera system. [ABSTRACT FROM AUTHOR]

Medium resolution CCD-spectrograph observations have been obtained that are suitable for studying long spatial wavelength 5-min oscillations. We find evidence that at wavelengths of order one solar radius the oscillation field is not isotropic. It is also not well described by modes of uniform excitation. The velocity power density per spherical harmonic increases with decreasing l to 1.1 × 10 cm s per 3.5 × 10 Hz angular frequency bandwidth at l = 4. These results are inconsistent with the data of Fossat and Ricort (1975) as analyzed by Christensen-Dalsgaard and Gough (1982), who found a substantially constant modal amplitude at intermediate l values. It is interesting that other calculations have seen a similar dependence at small l in the growth rate of p-modes due to the κ-mechanism. [ABSTRACT FROM AUTHOR]