High resolution observations of a sunspot region were obtained on October 3, 1994 with the Multichannel Subtractive Double Pass (MSDP) spectrograph. This instrument installed at the focus of the Vacuum Tower Telescope (VTT) at Tenerife (Canary Islands) operated in the Hα line. Intensity fluctuations and Doppler shift velocities at several wavelengths were derived over a two dimensional field of...

The magnetic, thermal and velocity structure of a regular sunspot, observed close to solar disk center is presented. Spectropolarimetric data obtained with the Tenerife Infrared Polarimeter (TIP) in two infrared Fe I lines at 15 648.5 Å and 15 652.8 Å are inverted employing a technique based on response functions to retrieve the atmospheric stratification at every point in the sunspot. In order...

The two-dimensional temperature distribution in a highly structured sunspot and in two small umbrae is determined from a three-colour photometry in narrow spectral continua. Disturbing influences from the earth’s atmosphere are removed by speckle masking techniques, yielding a spatial resolution limited by the telescope’s aperture. The corresponding colour temperatures are consistent over a ran...

In order to study umbral oscillations, running penumbral waves and the relationship between them, we analyzed CCD, high resolution, sunspot observations obtained at center and the wings of the Hα line and the Fe I 5576 Å line. The UBF filter was used in order to produce high cadence sequences of filtergrams. Images were processed to remove the sharp intensity gradient between the umbra and the ...

Context. Upflows in the corona are of importance, as they may contribute to solar wind. There has been considerable interest upflows from active regions (ARs). The coronal that seen at edges have elemental composition and can slow sources challenging determine because be multiple, spatial resolution previous observations is not yet high enough. Aims. In this article, we analyse AR 12960 unusual...

This paper describes two complementary algorithms developed for mobile robots operating within unknown, maze-type environments. The first is an environmental mapping and navigation algorithm which ensures complete coverage of a maze with apriori unknown wall locations, and the second a stochastic learning automaton approach for general obstacle avoidance within the maze. The environmental mappi...