Sayan Solar Observatory

From ISTP SB RAS

The observatory is located in mountains at an altitude of 2000 m. This location was chosen because of the specificity of main objectives which require high atmospheric transparency for polarization measurements and solar corona observations.

Contents

[edit] Main objectives:

  • measurements of solar magnetic fields
  • spectral observations of active solar features and dynamic processes in the Sun’s atmosphere


[edit] Equipement

  • Horizontal Solar Telescope with a magnetograph
  • Solar Telescope for real-time prediction
  • Non-eclipse Coronagraph

Main parameters:

  • Mirror (D = 800 mm; focal length – 20 m);
  • Spectrograph (focal length – 7 m);
  • Diffraction grating (200×300 mm, 600 lines/mm);
  • Equipment: vector- and panoramic magnetographs.

[edit] Multi-purpose automated solar telescope equipped with a set of magnetographs and spectrophotometers

The Horizontal Solar Telescope includes a celostat – a system of two flat mirrors 800 mm in diameter each for continuous observation of the Sun. The celostat directs sunlight to the main spherical mirror 800 mm in diameter and 20 m in focal length, which constructs an image of the Sun with the aid of a photodetector. The telescope’s optics is the largest in Russia in size and quality; AST is one of the world’s largest solar telescopes. It is equipped with a solar magnetograph for measuring magnetic fields and velocities of moving plasma in the Sun’s atmosphere and their time variations. AST has been used to prepare over 200 papers on problems of solar magnetism and plasma dynamics in the Sun’s atmosphere. The telescope provided first detailed images of an active region magnetic field emerging from the lower layers of the Sun to the surface as well as new regularities in the structure and dynamics of the magnetic field at different stages of active region evolution. It has been shown that the magnetic flux of an active region dissipates only partially during its evolution or leaves the Sun with a part diving back into the lower layers of the Sun. Peculiar properties of convective motions in an active region have been found: ring convective structures around a spot whose interaction with the magnetic field governs the stability of sunspots, their evolution and lifetime.


Main characteristics:

  • Type – two celostats (D = 300 mm);
  • Two refractors (D = 200 mm; focal length – 5 m);
  • Littrow spectrograph (focal length – 5 m);
  • Equipment: a magnetograph.

[edit] Problem-oriented Solar Telescope for Operative Prediction (STOP) for measuring large-scale solar magnetic fields

STOP is a special purpose telescope designed to observe magnetic fields of the Sun as a star and measure weak, large-scale magnetic fields on the solar surface. There are two types of main observational programmes:

1) Measurements of solar mean magnetic fields (SMMF);

2) Measurements of large-scale (background) magnetic fields with 120" angular resolution and 100" scanning rate in both coordinates, X and Y.

An automated system updated step by step has been in operation at STOP since 1992.


Main parameters:

  • Type – a telescope of the Nikolsky system with a 1-lens objective (D = 530 mm, focal length – 12 m).
  • Spectrograph (focal length – 8 m; grating – 300×300 mm)

[edit] Large Solar Coronagraph

The Large Coronagraph of the Sayan Observatory is designed to study the corona during non-eclipse periods and the chromosphere with very low scattered light. It is equipped with a spectrograph and narrow-band filters. In recent years, this coronagraph has been used to perform a series of investigations into dynamics of chromospheric spicules – fine-structure ejections of plasma into the solar chromosphere and corona. A number of new regularities in dynamic characteristics of spicules and their fluctuations yielded new information necessary to solve the intriguing problem of existence and mechanism of heating in the solar corona – the external solar atmosphere heated up to 1 million degrees, while the temperature of the visible solar surface is about six thousand degrees.

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