1993-04:   Overestimating the Coronal Density and Its Effect on the Velocities from Ly-alpha Doppler Dimming

Esser, R. & Habbal, S. R.

It is shown that relatively small errors of the order of 10% in the electron densities, for example derived from polarization brightness measurements, might lead to large errors in the velocities inferred from intensity measurements of the Ly-alpha H I 1216 Angstrom spectral line in the inner corona. It is demonstrated that in some cases this effect can result in very high velocities close to the coronal base with subsequent small acceleration with heliocentric distance. It is also pointed out that the errors in the deduced velocities can be reduced if simultaneous observations that place constraints on the mass flux are available, and by ensuring that the mass flux computed from the derived velocities and densities is constant. Solar Physics, 147, 241, 1993.

1993-03:   A Two-Dimensional MHD global coronal model: steady state streamers

Wang A.-H, Wu, S. T., Suess, S. T., Poletto, G.

1993, Solar Physics, 147, 55-71

1993-02:   Ly-alpha intensity in Coronal Streamers

Noci, G., Poletto, G., Suess, S. T., Wang A.-H, Wu, S. T.

1993, Solar Physics, 147, 173

1993-01:   Stray-light suppression in a reflecting white-light coronagraph


1993, Applied Optics (ISSN 0003-6935), vol. 32, no. 19, p. 3559-3569.

An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.