A moderate-resolution Nasmyth-focus spectrograph of the 6-m BTA telescope

We report on the development of a fast crossed-dispersion spectrograph (CRAB) mounted at the Nasmyth focus of the 6-m telescope. The spectrograph is designed for visible and near-infrared (3800–10 500 Å) CCD observations with the spectral resolution R=4000. We give the basic parameters of the optical scheme and the parameters of the echelle frame. We determined the gain involved in putting the spectrograph into observational practice and discuss the possible range of spectroscopic problems for which the instrument is optimal.     

High-resolution fibre-fed spectrograph for the 6-m telescope. Polarimetric unit

We report the computation of the design of a polarimetric unit for the optical scheme of the fiberfed high-resolution spectrograph for the 6-m Russian telescope.We discuss a variant of its integration into the design of conversion optics at the input of the fiber path if the instrument and estimate the efficiency of the entire pre-fiber optical system. The luminous efficiency of the assembly is equal to 80 and 90% when operated in the polarimetry and normal spectroscopic modes, respectively.We estimate the lower limit for the distorting instrumental effects of the polarimetric unit.     

Fiber-optic magnetometer for prime focus of 6-m BTA telescope based on suspended echelle spectrograph

We have developed and manufactured a fiber-optic magnetometer for the prime focus of the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences based on a suspended echelle spectrograph. The magnetometer is designed to improve the spectrum stability and eliminate the effect of instrumental polarization of the diagonal mirror on the results of magnetic field measurements. The magnetometer is to be used for measurements of stellar magnetic fields in stars and to study their chemical composition. The instrument operates in the 5000–6800 Å wavelength interval with mean reciprocal dispersion of 0.15 Å/pixel. According to the estimates for 9 ^m .5 stars, the standard error of magnetic field measurements based on 400 spectral lines would be 100 G for a half-hour exposure.     

Main stellar spectrograph of the 6-meter telescope. Analysis,reconstruction, and operation

The Main Stellar Spectrograph (MSS) of the 6-m telescope of the Special Astrophysical Observatory was developed in the early 1970s and has been in permanent operation since 1975. This instrument has been successfully kept operational for a long time by equipping it with modern detectors and significantly upgrading its optical layout. In this paper we present the main parameters of the optomechanical layout of the MSS, the design features of auxiliary devices, operational experience and statistics of the use of the instrument with various detectors, and the characteristics of the corresponding observational techniques.     

Spectropolarimetric observations of active galactic nuclei with the 6-m BTA telescope

We present the results of our spectropolarimetric observations for a number of active galactic nuclei (AGNs) carried out at the 6-m telescope with the SCORPIO focal reducer. The derived wavelength dependences of the polarization have been analyzed by taking into account the Faraday rotation of the polarization plane on the photon mean free path in a magnetized accretion disk. As a result, based on traditional accretion disk models, we have determined the magnetic field strength and distribution and a number of physical parameters of the accreting plasma in the region where the optical radiation is generated.     

Adjustment of a tower solar telescope and spectrograph: A method manual

Questions of the mounting and adjustment of a tower solar telescope are considered through the example of the TST-2 telescope of the Crimean Astrophysical Observatory Scientific Research Institute. The authors describe the optical circuits of the telescope and spectrograph and list the basic requirements for the mutual arrangement of individual components of the telescope. Simple methods for adjusting elements of the telescope and spectrograph are described.     

Ultraviolet observations with the space telescope Glazar

Byurakan Astrophysical Observatory; SKB Granit; Geneva Observatory; Flight Control Center. Translated from Astrofizika, Vol. 32, No. 1, p. 5–13, January–February, 1990.     

Magnetograph observations with the Swedish solar telescope on La Palma

A high-resolution videomagnetograph that records the images of opposite circular polarization simultaneously has been constructed for the Swedish vacuum solar telescope at La Palma. Magnetograms are obtained by off-line integration of bursts consisting of typically 50 frames of 20 ms exposures, with bad frames rejected, and the frame-to-frame image motion of the remaining frames compensated for by cross-correlation techniques. The short exposures combined with frame selection and elimination of image motion optimizes the resolution and thereby also the S/N, allowing good magnetograms to be obtained with an effective exposure time of less than 1 s at an image scale of 0.1 pixel^–1. The advantages and limitations of the system are discussed and compared with other techniques of making filter magnetograms are discussed.     

Nonthermal velocities in the solar transition zone observed with the high-resolution telescope and spectrograph

Data obtained during the first rocket flight of the NRL High Resolution Telescope and Spectrograph (HRTS) have been used to study nonthermal velocities for spectral lines primarily covering the temperature range 10⁴ to 2 × 10⁶ K. The high spectral and spatial resolution, combined with an enhanced dynamic intensity range of the reduced data, has enabled us to study the distribution of the nonthermal velocities for quiet and active regions. Average values of the nonthermal velocities peak at about 27 km s^–1 at 10⁵ K for the quiet regions, with a wide distribution of nonthermal velocities for each line. The active region nonthermal velocities have a narrower distribution which is weighted towards higher values. The SiIV and C IV line profiles are not well described by a single Gaussian, indicating that high-velocity components (above 30 km s^–1) are present in the quiet-Sun spectra. The radiative losses for all plasma above l0⁵ K have been calculated for the quiet Sun, an active region and a coronal hole. These have been compared with the acoustic wave flux inferred from the nonthermal line widths. There appears to be a sufficient flux of waves to heat these regions of the atmosphere.     

Photographic and spectrographic observations with a reducing camera on the 61 cm NCU telescope

A Reducing Camera designed by Meinel has been constructed and tested on the 61 cm NCU Cassegrain telescope. The basic principle of RC is to reduce the reflector'sf/13.5 to the equivalentf/2.7 such that the Cassegrain focus image can be reduced on a 35 mm film with almost no loss in sky coverage and in resolution but the exposure time is reduced by a factor of 25. The camera is able to obtain stellar spectra. With a grism and a standard lens the dispersion is 450 Å mm^–1, which is comparable to that required for the MK classification. RC constructure and testing results are reported. The method of a wide field spectrograph and that of narrow band differential photography of RC are also discussed.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Technique of polarimetric observations of faint objects at the 6-m BTA telescope

We describe the technique of spectropolarimetric observations allowing for the measurements of the Stokes parameters in one of the observational modes of the SCORPIO focal reducer of the 6-m BTA telescope of the SAO RAS. The characteristics of the instrument in the spectropolarimetric mode of observations are given. We present the algorithm of observational data reduction. The capabilities of the SCORPIO spectropolarimetric mode are demonstrated on the examples of observations of various astronomical objects.     

Design of 2-M to 6-M Liquid Mirror Containers

A new design is proposed for large (up to 6-m) liquid mirror containers. The design uses Kevlar, foam and aluminum, as in previous designs, but with a different configuration that makes the container lighter, stronger and more rigid. The results of finite element analysis are presented, consisting in the deformations due to temperature changes and to weight, and in the security factor for each material when maximum constraints are applied. Tilt rigidity is also analyzed. They show that the composite material construction technique gives a good performance up to 6 m diameters. The figures and tables contained in this paper can be used as recipes to build containers having diameters between 2 and 6 m. This revised version was published online in July 2006 with corrections to the Cover Date.     

New vacuum solar telescope and observations with high resolution

The New Vacuum Solar Telescope(NVST) is a one meter vacuum solar telescope that aims to observe fine structures on the Sun. The main goals of NVST are high resolution imaging and spectral observations, including measurements of the solar magnetic field. NVST is the primary ground-based facility used by the Chinese solar research community in this solar cycle. It is located by Fuxian Lake in southwest China, where the seeing is good enough to perform high resolution observations. We first introduce the general conditions at the Fuxian Solar Observatory and the primary science cases of NVST. Then, the basic structures of this telescope and instruments are described in detail. Finally, some typical high resolution data of the solar photosphere and chromosphere are also shown.     

High-resolution fiber-fed echelle spectrograph for the 6-m telescope. I. Optical scheme,arrangement, and control system

We propose a project of a high-resolution (R = 100 000) fiber-fed spectrograph for comprehensive studies of stellar atmospheres, exoplanet searches, asteroseismological studies, studies of stellar magnetism, active nuclei of bright galaxies, interstellar medium, etc. We present the optical scheme of the instrument. The operating wavelength region spans from 4000 to 7500 Å. We also present the optical scheme of the pre-fiber optic unit of the spectrograph. The unit supports four main modes of spectroscopic observations: the mode of traditional spectroscopy with the spectrum of the studied object taken along with the background spectrum in the immediate vicinity of the object; the mode of the simultaneous recording of the spectrum of the object and that of the wavelength standard; the mode of high-precision spectroscopy with an iodine cell, and the mode of spectropolarimetric observations with the measurement of all the Stokes parameters.     

Small-scale galactic emission fluctuation observations with RATAN-600 radio telescope

We present the estimates of Galactic synchrotron and free-free emission power at intermediate and small scales (500 < l < 1000, 20′ < θ < 40′), based on the RATAN-600 radio telescope observations (SAO RAS). The observations were conducted in the frequency range of 2.3–11.2 GHz using the transit scan mode, in the declination range of 40.7° s δ < 42.3°. The power spectrum estimates of synchrotron and free-free components were obtained. They can be further used in the data processing stage of the high-resolution cosmological experiments like Planck.     

Astronomy with a mid-infrared echelle spectrograph

Irshell, a mid-infrared echelle spectrograph developed through a collaboration between the University of Texas, the University of California Space Sciences Laboratory, and Hughes Aircraft, has been in regular use for astronomical observations for about five years. It is optimized for high spectral resolution (R10,000) observations of narrow spectral regions (/1/300) and compact sources (a few arcsec), and is sensitive in the 5–25 m region. A wide variety of astronomical objects have been studied. Observing techniques have been developed to achieve maximum sensitivity in those observations for which Irshell is best suited and to allow observations of wide spectral regions and extended objects. We discuss the observing techniques and show some of the data obtained.     

High resolution fabry-perot and multi-pupil spectral observations of the genuine blue compact dwarf galaxy IZW18

We present the observations of the BCDG IZW18 performed with a Fabry-Perot interferometer at the CFH 3.6 m telescope and with a multi-pupil spectrograph at the SAO (Russia) 6 m telescope. The morphological structure of the galaxy in emission lines and in continuum, the velocity field of the ionized gas, and [OIII]/H ratio distribution along the NW component have been investigated. Besides the NW and SE HII components, we find a population of small HII regions. Continuum maps show that the peaks of the stellar light distribution are displaced with respect to the emission lines maxima. the velocity field shows peculiar motions superposed on an approximately regular background implying solid body rotation. Emission line profiles exhibit an asymmetric structure, except for the NW compact component. The [OIII]/H ratio decreases from the center of the NW component to its edge with the gradient of 1.86 kpc^–1.Published in Astrofizika, Vol. 38, No. 4, pp. 602–615, October–December, 1995.