In order to study the solar corona during eclipses, a new telescope was constructed. Three coronal images were obtained simultaneously through a single objective of the telescope as the coronal radiation passed through three polarizers (whose transmission directions were turned 0°, 60°, and 120°in the chosen direction); one image was obtained without a polarizer. The telescope was used to observe the solar corona during the eclipse of 1 August 2008. We obtained the distributions of polarization brightness, K-corona brightness, the degree of K-corona polarization and the total polarization degree; the polarization direction, depending on the latitude and radius in the plane of the sky, was also obtained. We calculated the radial distributions of electron density depending on the latitude. The properties of all these distributions were compared for different coronal structures. We determined the temperature of the coronal plasma in different coronal structures assuming hydrostatic equilibrium.

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The devices and components of adaptive optical system ANGARA, which is developed for image correction in the Big solar vacuum telescope (BSVT) at Bayk al astrophysical obse rvatory are descri bed. It is shown t hat the use of modernized adaptive system on BSVT not only reduces the turbulent atmospheric distortions of image, but also gives a possibility to improve the telescope de veloping new methods of solar observations. A high precision Shac k-Hartmann wavefront (WF) sensor has been de veloped on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640X640 μm with an error not ex ceeding 4.80 arc.sec. Also the modification of this sensor for adaptive system of solar telescope using extended scenes as t racking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of lo cal WF slopes esti mation (modified centroids, normalized cross-correlation and fast Fourier-demodulation), as wel l as t hree methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

A chromospheric telescope is an important instrument for synoptic observations and solar research. After several decades of observations with the chromospheric telescope at Baikal Astrophysical Observatory, a need arose to improve the characteristics of this telescope and filter. A new reimaging lens to produce full-disk solar images 18 mm in diameter at the CCD camera Hamamatsu C-124 with a detector 36×24 mm (4000×2672 pixels) was designed and manufactured to replace the out-of-operation 50×50 mm Princeton Instruments camera. A contrast interference blocking filter and a new Iceland spar and quartz crystal plates instead of damaged ones were made and installed in the Hα birefringent filter (BF), manufactured by Bernhard Hallе Nachfl. The optical immersion in the filter was changed. All telescope optics was cleaned and adjusted. We describe for the first time the design features and their related BF passband tuning. The wavefront interferograms of optical elements and telescope as a whole show that the wavefront distortion of the optical path is within 0.25 λ. The BF and pre-filter spectral parameters provide high-contrast monochromatic images. Besides, we give examples of solar chromospheric images in the Ha line core and wing.