The Baikal Astrophysical Observatory (BAO) located in the Settlement of Listvyanka (104°53'30 E, 51°50'47 N), on the southwest shore of Lake Baikal, 70 km from Irkutsk, occupies 51.06 hectares. A large water area of the lake, the existence of a local anticyclonic zone and geographical features of the region enable long periods of the stable quality for images during daytime, particularly in separate seasons.

Mission:

• Monitoring solar activity to conduct fundamental and applied research within Russian and International scientific programs;
• Spectral, spectro-polarimetric, and filter observations of non-stationary processes in the solar atmosphere to study mechanisms for their emergence;
• Developing and testing new devices and instruments.

Telescopes:

• Large Solar Vacuum Telescope (LSVT);
• Full Disk Нα (656.3 nm) Telescope;
• Full Disk K CaII (393.4 nm) Telescope;
• Solar Telescope for Operative Predictions (of new-generation) STOP-1;
• Solar Synoptic Telescope (SOLSYT), at the commissioning stage.

The LSVT is among the top ten largest solar telescopes in the world. It is also on the List of Unique Facilities in the Russian Federation (No. 01-29). USSR AS Correspondent-Member V.E. Stepanov put forward the idea of building such an instrument at Baikal. The telescope has unique optical characteristics enabling to observe fine-structure formations on the Sun at high quality, to study physical processes in the solar atmosphere at high spatial, spectral, and temporal resolutions.

Specifications:

The telescope catadioptric optical system involves a polar 1-m siderostat, two-lens achromatic 0.76-m objective with a 40-m focal length, and a spectrograph. A slant 40-m telescope pipe is within a metal airproof body closed from above and from below by transparent plane-parallel plates. To eliminate air density fluctuation effects on the image quality, there is a special facility enabling to vacuumize the telescope, by reducing pressure inside the pipe to several millimeters of mercury. The LSVT is equipped with a highly-dispersive spectrograph that facilitates to determine physical properties of the solar plasma (travel velocity, chemical composition, magnetic field), as well as to estimate the temperature, microturbulence velocity, and electron density.

Spectrograph specifications:

The spectrograph optical train represents the Ebert-Fastie system with a 15-m focal length. There are two camera mirrors in the spectrograph, which enables to simultaneously record various regions of the solar spectrum. To obtain polarization spectra and calculate the Stokes parameters, the spectral slit is supplied with a rhombohedron and phase plates. Thereby, in the camera section of the spectrograph, four spectra are formed: two spectral regions in different polarizations. Recording the spectra is done by a FLIGrab wide-format (2048×2048 px) CCD-camera. Simultaneously with the spectra, one records the Sun in the Нα in the light reflected from the spectrograph mirror slit with a narrow-band (5 nm) interference-polarization filter and a (512x512 px) Princeton Instruments CCD-camera.

The actual spatial resolution within the telescope-spectrograph suite reaches 0,4". Recently, a team of researchers and enginneers have been upgrading the LSVT, developing an adaptive optics system to improve the image quality.