Scientific achievements, Hardware and methodological developments
2008
New Fourier spectrum analyzer for radio astronomy research at the RATAN-600
A new digital Fourier spectrograph with the analysis bandwidth of 60 MHz and 2048 spectral channels was put into operation at the RATAN-600. Getting information about the studied signal in the time-frequency-power measurements allows recording and analyzing the signals, rapidly varying in time. The use of this device facilitates the separation of radio astronomical signals from noise — the registration of a broadband signal, divided into a large number of narrow areas provides the capability to eliminate the distortions, introduced by the interferences stable in frequency. The presence of information about the moment of registration in the recorded signal allows to exclude the short-term broadband spark-type interferences.
In collaboration with IAA, ASC LPI RAS, Institute of Isotherms.
(Contact — A.P. Venger).
2007
Accuracy of Radial Velocity Measurements Enhanced on BTA
As a result of usage of an absorption cell, the accuracy of measurements of Doppler shifts on BTA's stellar spectrographs was increased by more than an order (Δ Vr = 20-30 m/s).
Program for Finding Photometric Distances to Nearby Galaxies
A programme was elaborated to measure high-precision photometric distances to nearby (resolved into stars) galaxies according to the Tip of the Red Giants Branch (TRGB) method. The use of a maximum likelihood method and photometric accuracy assessment with an application of expanded statistical modeling of dense star fields allowed to increase the accuracy of distance finding using the TRGB method up to 5-8%, which is comparable to the accuracy of a Cepheid distance indicator. This method has no equal as of its versatility and short observation times.
Test Observations on RATAN-600 with MARS-3 16-Channel Matrix System
First observations were made on RATAN-600 with a unique MARS-3 16-channel (32 inputs) Matrix Radiometric System that has no analogue in Russian radio astronomy. The use of such system in a mode when radio sources propagate through a fixed diagram of the antenna, allows quadrupling of radiotelescope's sensitivity compared to one-channel radiometer and decreases the time of signal collection from weak objects by 16 times.
Centre for Analysis of Multiwave Observations Created on RATAN-600
An on-line processing centre for analysis of multiwave radio observations of the Sun on RATAN-600 was created in the St. Petersburg Branch of SAO RAS, see http://www.spbf.sao.ru/prognoz/. Its functions include automatic polling of multiwave length data from RATAN-600, all radioheliographs and satellite observatories; full data processing and correlation, and multi-format submission to the end users. The Centre is dedicated to the creation of a generalized forecast of solar activity based on detailed spectrum of radio frequency observations of the Sun and for students' labs.
2006
A high angular resolution (0.4") was reached at the BTA as a result of use of an image stabilizer, coupled with the optical image cutter and a specialized echelle spectra reduction algorithm during the observations with high spectral resolution (R = 75000) in the wavelength range of 450-650 nm. This made it possible to study the properties and spatial distribution of the circumstellar matter in objects, located in our Galaxy at the distances of about 2 kpc.
A method for suppressing the background noise of radio sources was developed and implemented at the RATAN-600, allowing to increase severalfold the penetrating ability of the major Russian shortwave radio telescope.
2005
Creation of the distributed net of control (DCN) of the 6 m telescope has been completed, which is based on the use of digital tracking drives and the means of commercial automatization to ensure the real-time processes of control and data acquisition. With changing to DCN, computer diagnostics of the majority of units of the telescope has been implemented, the reliability of its operation in the whole has been increased, its performance characteristics have been improved. The created original software permits flexible change and reconstruction of the telescope units and involve new service functions.
For the solar spectral-polarization complex of high resolution of RATAN-600 input feeds of circular polarization allowing measurement of extreme polarization degrees in a range of 6-18 GHz have been created. Data acquisition system for registering 64 channels with a speed of 1 millisecond per channel and software for reduction of multiwave observations allowing comparison with the data of the main ground-based and space solar observatories have been developed. Complete automation of the complex performance in the mode of adaptive selection of amplification, control of the current parameters, channel smoothing of a spectrum to an accuracy of 0.5% etc. have been implemented.
The first Russians Internet opened visual monitoring system is developed and put into operation for the SAO RAS 6 m telescope. That makes it possible for the operators and observers to inspect remotely the state and performance of the basic telescope systems, pointing control and weather conditions.
2004
Creation of a unique set of the spectral and polarization complex of high resolution in the range of 6-18 GHz, consisting of 64 channels with a 1% analysis stripe was concluded. Based on the combination of key parameters — the frequency overlap and resolution, sensitivity and accuracy of polarization measurements, such a complex is the first instrument of its kind in the practice of solar astronomy.
A new cryogenic radiometer with the sensitivity close to the limit on the surface of the Earth was developed, manufactured and implemented for normal observations at the RATAN-600. The radiometer operates at the dedicated frequency for the radio astronomy, 4.8 GHz (6.25 cm), uses both modes of circular polarization with a separate amplifier channel for each mode, and implements an additional gain in sensitivity owing to the absence of losses due to the splitting of circular modes in the aperture of the RATAN-600.
2003
As a result of development of image slicers, polarization analyzers and reduction technique, the limiting magnitude of spectral observations at BTA with high spectral resolution (up to R = 80000) has been increased by 3 times, the limiting magnitude of spectropolarimetric observations increased from 3 to 8 times (in the red and UV ranges, respectively).
A wide-angle system (18×20 degrees) of high time resolution (up to 0.13 s) for real time detection of variable astronomical objects — optical transients of gamma-bursts, flare stars and novae, supernovae at early stages of their birth, and also near-earths moving bodies of natural and artificial origin — is created.
In co-operation with Kosmoten and SRI RAS
2002
A quartz echelle spectrograph with a large diameter of the collimated beam (NES) equipped with a CCD (2048×2048 elements) was designed, manufactured and put into operation in the Nasmyth focus of the 6-m telescope. The spectrograph provides the spectral resolution of up to R = 82000 in the wavelength range of 320-1000 nm. The information content of observations with high spectral resolution at the telescope is increased tenfold.
In collaboration with the University of Uppsala (Sweden)
A new-generation CCD system with the cryostat matrix detector sized 2048×2048 elements was designed and put into operation at the 6-m telescope. Digital video signal filtering and correction of the light transmission characteristics were implemented for the first time. This provides the limiting sensitivity and photometric stability for the astronomical practice. The readout noise is reduced by 30-40% compared with the traditional methods of data reduction (with the EEV CCD42-40 - 1.7 electrons). The residual nonlinearity does not exceed 0.03%, and relative photometric instability does not exceed 0.06% over 24 hours. Production of such systems with the CCD42-40 for the 6-m telescope is tailored.
In collaboration with the Institute of Applied Physics of the RAS
We have developed and tested the model of a new-generation three-element broadband radiometric matrix system at the RATAN-600 extremely short wavelength of 1 cm, allowing a large replication to over 100 elements. The sensitivity of 6 mK reached without cooling is close to the sensitivity of the cryogenic radiometers of the RATAN-600 in the given range.
New electrodynamic calculations of the RATAN-600 power beam pattern, including the diffraction effects and the account of the finite size width of the primary mirror aperture are in good agreement with the experimental measurements over a wide wavelength range and a large solid angle, conducted in 2002. These measurements and the power beam pattern calculation programs increase the accuracy of measurements of the flux densities and radio brightness distributions of extended cosmic sources, and are used in the data processing and modeling of the recent and future radio surveys featuring the radio source counts, and in the studies of the anisotropy of the cosmic microwave background.
Creation of a basic high speed Ethernet information computer network of the SAO RAS has been accomplished. It now provides access to the BTA and RATAN-600 telescopes at 155 Mbit/s based on the 27 km-long fiber optic link. The outgoing Internet speed reached is 2 Mbit/s.
2001
A new-generation SCORPIO spectrograph was created for the primary focus of the BTA. It allows observations of extended and starlike objects in different modes: CCD photometry, panoramic spectroscopy with the Fabry-Perot interferometer, spectroscopy and spectropolarimetry with a “long-slit”, slit-free spectroscopy, multi-object spectroscopy. In the spectral observations mode the instrument is 5-6 times superior in the efficiency to the existing spectrographs of this class at the BTA and is comparable to the best world analogues.
The reconstruction of the azimuth axis drive of the BTA is completed. Digital servo drives that were installed have improved the reliability of the complex, extended the range severalfold, and reduced the telescope's speed control step. The implementation of such drives provides a basis for the distributed control system of the BTA complex.
A new system of automated control of the RATAN-600 flat reflector was put into operation. It allows to increase the productivity of its use by an order of magnitude and develop new observational modes. The mode of multi-azimuth observations using an automated flat reflector, the South sector and a high-precision digital drive of the receiving cabin irradiator 3 was implemented.
The work on improving the accuracy of the reflecting surface of the RATAN-600 antenna was completed. As a result, the standard error of individual reflecting elements was improved to about 0.2 mm.
A software and hardware set for the BTA control system was implemented. It allows for the network monitoring of the telescope in different modes, including the display of video from the guide and service camcorders of the BTA. Three types of interface were carried into effect: the user, operator and Web-interfaces.
A digital archive was compiled, covering the observations at the RATAN-600 in the continuum for over 23 years of operation.
1999
A new fiber multiobject spectrograph of the prime focus of the BTA was manufactured, designed for the spectroscopy of low and moderate spectral resolution of up to 70 objects at once, visible in the telescope's field of view sized 12'. A metalized mask was inserted in the focal plane of the telescope, where with the aid of magnets the quartz fibers were fixed, transmitting the light in the focal plane of the collimator in the shape of a long slit. The new spectrograph brought an opportunity to explore the objects with absolute magnitudes m = 22-23 in the R-band. In 1999 the spectrograph was used for the BTA observations within two programs.
After many years of work, the multi-frequency (matrix) radiometer with the fluctuation sensitivity above 10 mK/s at all operating channels was completed and turned into operation at the RATAN-600 radio telescope.
We have extended (20-fold in the analysis strip) the capabilities of extragalactic research at the RATAN-600 in the 21 cm line with the introduction of a 50 MHz spectrum analyzer operating on the principles of acousto-optics.
1998
Creation of the world's largest database of radio astronomical catalogs, designated CATS was completed, which is now free and available online at the web server cats.sao.ru. It includes the data of X-ray, optical, infrared and radio wavelength ranges on 4.5 million space objects from 300 catalogs (the radio astronomical catalogs were presented in full for the first time).
1997
The parameters of the unique solar complex at the RATAN-600 were enhanced. Determined by the unit's instrumental errors, the maximum accuracy of polarization measurements was reached on the panoramic spectrum analyzer PAS of the RATAN-600: 0.02-0.03% in the measurements over the entire solar disk, and 0.2-0.3% in the measurements of point sources. Automation of the complete cycle of solar observations with the RATAN-600 was finalized, with the daily multi-wavelength observational data outputs to the Internet via the SAO servers and SOHO satellite.
A coude-echelle spectrometer of high and very high resolution was designed and manufactured for the 2-meter telescope (Terskol peak) with the simultaneous spectrum registration in a wide wavelength range (3500-10000 A) by the CCD system. The spectrometer has three Schmidt cameras that enable spectral observations with the resolution of R = 45000, 90000, 180000. For a 10m star during the 1 hour exposure time, the S/N ratio equal to 100 is reached at R = 45000. By its main characteristics the instrument is comparable to the best world systems of the class, which allows solving a large variety of astronomical tasks in the spectroscopy at the contemporary level, requiring a high spectral resolution.
1996
The highly effective method controlling a wide class of radio interferences in the most sophisticated UHF band was put into practice of observations.
1995
A new-generation automated control system of the antenna in two sectors of the RATAN-600 circular reflector was put into regular operation. The reliability and dynamics of the system were increased by 10 times, while the accuracy and repeatability doubled. This allows measuring the flux densities of radio sources in the shortwave range with an accuracy of about 1%. In 1995, 8000 observations were made at the level of system failures of less than 0.2%.
Alignment and stabilization of the surface (225 elements) of the RATAN-600 northern sector were performed, resulting in the RMS surface accuracy increase from 1.0-1.3 mm to 0.18 mm. This has augmented the effective area of the northern sector by 70% at the wavelength of 1.38 cm. The achieved parameters improve the efficiency of the observing time usage at RATAN-600 in the shortwave range by several times.
1994
World-class sensitivity was reached at the RATAN-600 radio telescope in three centimeter wavelengths (2.7, 3.9, and 7.6 cm): 3.2, 3.4 and 2.5 mK/s, respectively through the introduction of cryogenic low-noise amplifiers based on the high electron mobility transistors (HEMT) in the radio astronomy observations.
A new-generation 2D-spectrograph featuring a CCD, mounted inside the high-aperture Schmidt camera was developed and put into service at the BTA telescope. In the visible spectral range (3000-10000 A) the quantum efficiency of 6-8% was reached, which corresponds to the world standards for the instruments of this type.
The prototype of the fluctuation damping circuit, which reduces the vibrations of the telescope in terms of the decay time by 5-6 times was developed and mounted at the BTA. The ability to create high-precision control systems for the BTA and other alt-azimuth systems with an order of magnitude higher precision characteristics under the wind loads on the telescope was experimentally demonstrated.
1993
We have mastered the technique of generating the secondary standards for the astrometric reference of images obtained using the CCDs at the BTA with the accuracy to one second of arc, based on the on prints from the Palomar maps using the Guide Star Catalog and a digitizer.
For the first time a device for quasi-simultaneous measurements of linear polarization of stars was developed, which allows to make up to 40% more efficient the use of the telescope time and significantly increase its accuracy. The device is protected by a patent.
Fast systems of high spectral resolution were developed and put into operation at the 6-m BTA and 1-m Zeiss telescopes, consisting of the echelle spectrometers, solid-body light detectors (CCDs), data acquisition and data processing systems. Judging on the basic photometric and positional features, the CEGS coude-echelle spectrometer is on par with the UCLES of the Anglo-Australian 3.9-m telescope and the Hamilton Echelle Lick (3-m telescope, U.S.), being second only in the CCD size. The echelle spectrometer, operating in the red band (“Lynx”) is not inferior to the CASPEC echelle spectrometer of the 3.6-m telescope of the European Southern Observatory based on its main characteristics.
The work on “cooling” the RATAN-600 has been accomplished. The flaps that reduce the contribution of the Earth below the temperature of the sky were installed. At the same time, the range was expanded up to 1.3 meters and the effective area at the decimeter waves was increased.
For the first time in radio astronomy observations in Russia a new type of amplifier (based on the HEMT transistor type) as part of the cryogenic radiometer at the 2.7 cm wavelength with a record sensitivity in this range of about 3 mK/s was introduced.
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