The Sun's radiation becomes linearly polarized by coherent scattering processes in the solar atmosphere. With a novel polarimetry system that achieves a precision of 1e-5 in the degree of polarization, the previously largely unexplored territory of …
The profiles of Stokes I and V of FeI 5247A, CrI 5247A, FeI 5250.2A and Fe I 5250.6A have been measured in the quiet photosphere with ZIMPOL, a new polarimeter, with very low noise level. The spatial resolution element of about 1Mm was essentially …
Phase-diversity techniques provide a novel observational method for overcoming the effects of turbulence and instrument-induced aberrations in ground-based astronomy. Two implementations of phase-diversity techniques that differ with regard to noise …
We have obtained images in solar coronal emission lines under high sky- background conditions by making precise differential measurements between the coronal emission line and the near-by continuum, which is primarily due to scattered light from the …
For about two weeks in 1995, the balloon-borne Flare Genesis Experiment will continuously observe the Sun well above the turbulent, image-blurring layers of the Earth's atmosphere. The polarization-free 80 cm telescope will supply images to a …
First observations of the full Stokes vector in the upper chromosphere are presented. The He I 10830 ̊A line, which has been shown to give reliable measurements of the line-of-sight component of the magnetic field vector, has been used for this …
Recent instrumental developments in imaging polarimetry allow array detectors to reach a polarimetric sensitivity of 1 × 10$^-4$ of the intensity. New instrumental effects appear at these levels of sensitivity and generate spurious polarization …
Observations of the full Stokes vector in three spectral lines indicate that flux tubes in solar plages have an average inclination in the photosphere of 14deg with respect to the local vertical. Most flux tubes are inclined in the eastwards …
We present a method to obtain diffraction limited spectrograms of extended sources from a series of ground-based slit- spectrograms. The method is a combination of speckle deconvolution (Keller & von der Luehe 1992) and a rapid spectrograph …