The Baikal Astrophysical Observatory (BAO)


(Link to this page as [[Baikal Astrophysical Observatory]])


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.


  • 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.


  • 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.


[edit] Large Solar Vacuum Telescope (LSVT)

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.


25-m tower height
1-m siderostat mirror
0.76-m main objective
40-m equivalent focal length
32' field-of-view
0.38-m solar image
0.2" spatial resolution

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:

0.6-m camera mirrors
15-m focal length of camera mirrors
9-m focal length collimating mirror
600 gr/mm 200×300-mm grating
0.0007-nm on-the-job resolution

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.

[edit] Main results

The LSVT main observational objects are solar flares. As per the present-day views, at the coronal flare onset, there is an energy release, and then one records chromosphere heating. The heating mechanism related to the flare origin is one of the most compelling scientific challenges. The energy transport from the corona into the chromosphere is possible due to thermal conductivity, X-rays, as well as via beams of charged particles. Although there is no uniform theory for flare formation, the latter mechanism has dominated lately. There are observations exhibiting a good spatial coincidence between X-ray sources and the position of solar-flare emissive cells in the chromosphere. One may elucidate X-rays through electron and proton deceleration in the dense chromospheric layers. Once assumed that beams of particles impinge on the chromosphere radially, the maximal polarization should be observed for the flares that are on the Sun limb, i.e., the spectral line polarization degree should depend on the flare position within the solar disk. The main investigations with the LSVT aim to study the above processes.

Based on observing a great number of solar flares, proven was the existence of shock linear polarization in some solar flares. The difference in the Stokes parameter profiles at various flare regions enabled to estimate the type and energy of energetic particles participating in chromosphere heating, as well as the particle beam penetration depth into the chromospheric layers. These results evidence that, during solar flares, energetic particle fluxes transport energy from the corona into the chromosphere.

[edit] Full Disk Нα Telescope

The telescope was designed and made at the ISTP SB RAS in 1980, as per a genuine optical scheme. The instrument was mounted in a stationary tower with a 5-m dome at the 12-m height 150 m from the Baikal shore (75 m above the lake level). Specifications:

0.18-m main objective
5.432-m equivalent focal length
50-mm image diameter
34' non-vignetted field-of-view
0.92" disk-center spatial resolution

In the telecentric ray path, there is an Нα (656.3 nm) Bernhard Halle Nachfl. GmbH interferential and polarization filter with a 0.05-nm half-width of the bandwidth and with a ±0.1 nm shift. Due to the genuine optical scheme, the telescope (as per the main characteristics) does not yield to the American Lockheed Telescope and outperforms the German Opton.

Until 2000, the telescope used an 80-mm film camera. In 2000-2002, a 2048x2048 Princeton Instruments CCD-matrix detector was used in observations. Since 2008, the full-disk chromospheric telescope has been equipped with a C9300-124 Hamamatsu CCD camera with a 2760×4000 detector. The observational archive on films and in e-form is stored at the ISTP SB RAS.

High-angular full-disk observations (including those of over-the-limb structures) enabled to state the following scientific goals:

  • investigating the fine structure of the chromosphere, filaments, and prominences;
  • studying solar flares;
  • monitoring solar activity at the chromosphere level;
  • investigating solar activity complexes;
  • studying the phenomenology of chromospheric formations including the application of fractal methods.

[edit] Main results

[edit] Full Disk K Call Telescope

K CaII observations enable to estimate a full magnetic flux, as well as to study the nature of rapid changes in large-scale magnetic fields and the magnetic field fine-structure dynamics in polar regions during the polarity reversal of the Sun general magnetic field.

The telescope was designed and manufactured at the ISTP SB RAS as per the optical scheme similar to that of the Full Disk Нα Telescope. In the telecentric ray path, there is a Bernhard Halle Nachfl. GmbH interferential and polarization filter with the 0.06-nm half-width of the bandwidth.


0.18-m main objective
34' non-vignetted field of view
5.154-m equivalent focal length
1' estimated spatial resolution
48-mm image diameter

The telescope has been in operation since 1995. Until 2003, the image was recorded on the 80-mm film. In 2003, the optical scheme was changed to record images with the 1704×2272 px Sony CyberShot DSC-S85 digital camera.

[edit] New-Generation Solar Telescope for Operative Predictions (STOP-1)

General information on the instrument:

full name Solar Telescope for Operative Predictions
contracted name STOP-1
established 2010 Nov 13
designer & manufacturer ISTP SB RAS
affiliation Baikal Astrophysical Observatory (Russia)
mission pioneering study of the velocity field and magnetic field of the Sun photosphere at the ~30" spatial resolution
physical principals of measurement methods Zeeman and Doppler effects
basic measurement methods photoelectric, differential, polarization, spectral, spatial at different angular aperture
wavelength operation range visible, NIR
radiation detectors multichannel CCD receivers
observational operators 1

[edit] Mission and main measurement characteristics

STOP-1 is intended to receive daily magnetograms of the full solar disk with the 30" angular aperture at the solar photosphere level in quasi-real time, as well as to record the distribution of the Stokes parameters in various spectral lines of the solar photosphere.

Main measurement data:

and their values are not distorted by theoretical approximations.

[edit] Instrument structure and specifications of systems

Systems and nodes:

Specifications of subsystems:

[edit] Operation principle

The instrument contains a horizontal solar refractory telescope with the Littrow spectrograph optically conjugate with it. By using this system, one makes the spectrum image in the selected wavelength segment for the set site of the Sun image. Scanning the image and fine guiding is performed with the CCD camera and with the coelostat mirror drives. They displace the image relative to the spectrograph entrance slit and measure its position in the tool's coordinate system. Scanning the image is stepwise by the set law. Simultaneously, the CCD camera records the distribution of spectrum band intensity for each site of the Sun image, as well as the current time and coordinates.

To measure the Stokes parameters, one uses the electrooptical analyzer located behind the spectrograph entrance slit. For each state of the analyzer, one measures the intensity necessary and sufficient to further calculate the Stokes parameters. The tool polarization is accounted for by the phase plates installed in front of the coelostat. Herewith, only the desired signal is modulated, whereas all the tool-originated signals remain invariable, which enables to split the signals into the solar- and tool-origin.

Measuring the magnetic field is based on the Zeeman effect for the photospheric absorption lines. These measurements do not differ methodically from those of the Stokes parameters. The multichannel sensor enables simultaneous observations in several magneto-sensitive lines in the ~4 Å spectral range.

Radial velocities of the Sun substance motion are measured by using different Doppler effect of reference points. One always measures the Doppler velocities at polarization observations in order to improve the data quality.

The system of data control, record, and procession enables to save data, pro-process them, to visualize the measured parameters in quasireal time, as well as to control the telescope in the interactive mode.

[edit] Solar Synoptic Telescope (SOLSYT)

In heliophysics, increasing attention is paid to regular long-term measurements of magnetic fields encompassing the entire solar surface. Only possessing such information, one can (at certain assumptions) calculate the parameters of the heliosphere and to predict geoeffective phenomena. Therefore, researchers pay notable attention to creating the instruments capable of conducting such observations. To reduce Russia's lag in this field (as compared with the advanced countries), a few years ago, the ISTP SB RAS in cooperation with the LOMO PC launched the program to design and manufacture a new instrument: SOLar SYnoptic Telescope (SOLSYT).

The telescope involves two main components: an objective and a spectrograph. The objective is the Mersenne system comprising two off-axis parabolas, and an intermediate slit node with a heat exchanger cooling down to the environment temperature. In the parallel beam (a significant condition for the used electrooptical polarization analyzer, because f-o-v errors are eliminated), there is a rotating rack with the interference filters in front of the apochromatic objective after the secondary mirror and the polarization analyzer.

Main mirror specifications:

2.799-m focal length
0.35-m entrance pupil
1:8 relative aperture
35.4' angular field-of-view
0.5-1.8 µm spectral range
0.4" estimated resolving power

One builds the Sun image on the spectrograph entrance slit by using the apochromat objective, in which chromatism is corrected for the 525, 630, 850, and 1085 nm wavelengths, and aberrations are replenished at the operation with an extended source.

SOLSYT spectrograph parameters at observations in the main operation lines

Wavelength, Å Diffraction angle Diffraction order Dispersion, Å/mm
5250 51.96 10 0.646
6300 49.12 8 0.875
8500 49.91 6 1.404
10830 54.47 5 1.521
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