RT-22 Radio Telescope Research Articles

Spectroscopic Observations in the 3-mm Wavelength Range at CrAO RT-22 Radiotelescope Using an Acousto-Optical Spectrum Analyzer

Within the framework of a multi-year program of dense interstellar gas studies, we performed a new series of observations at the CrAO RT-22 radiotelescope in July 1998 using an improved 3-mm wavelength receiving facility. An acousto-optical spectrum analyzer (AOS) was used for the first time for the spectral analysis of incoming radiation. The AOS has larger bandwidth compared to the filter spectrum analyzer used previously and simplifies tuning SIS-mixer circuits and frequency converters. Using this facility, we observed a number of star-forming regions including clouds associated with bright IR sources and ultracompact HII regions as well as clouds with high-velocity outflows in the HCO+, 13CO, HCN, and CS molecule lines.

Investigation of the H2O maser emission in G43.8-0.1

Observations and analysis of the H2O maser emission source, associated with the star-forming region G43.8-0.1, are presented. The observations were carried out on the RT-22 radio telescope of the Pushchino Radio Astronomy Observatory (Russia) in 1994–1998. A new flare of emission of a group of features at radial velocities from 37.5 to 39.5 km s-1, which took place in 1996–1998, was observed. For the 38.2 km s-1 feature, a dependence between flux density and linewidth () was derived; it indicates that the maser is unsaturated or partly saturated. The evolution of emission of the 42.2 km s-1 maser condensation is traced at a timespan of 16 years. The flux density was plotted versus linewidth for this feature (in the coordinates). This dependence contains two branches, largely shifted with respect to each other. The transition from one branch to the other took 2.5 years, while the linewidth was fluctuating. Possible causes of existence of the two branches in the maser emission evolution are discussed. An analysis of the entire data set for 1976–1998 has shown that the time interval between the minima of integral flux in G43.8-0.1 was 18 ± 1 yr. This figure can be taken as the period of the H2O maser activity in G43.8-0.1.

Determining the period of the long-period activity of the water-vapor maser in W75N

We present the results of our study of the H2O maser emission from the source W75N, which is associated with a star-forming region, between November 1994 and March 1999. The observations were carried out with the RT-22 radio telescope of the Pushchino Radio Astronomy Observatory (Lebedev Physical Institute). The maser emission in 1994–1999 can be represented as a superposition of flares of separate components with a duration from two to six months, which occurred mainly in the radial-velocity range 8–17.5 km s−1. We detected a regular drift of the velocity centroid from 13 to 9 km s−1 and an abrupt change in its velocity from 9 to 5 km s−1, which took place at the initial stage of maser activity. Based on the variability of the total H2O flux in all years of our observations of W75N (from December 1979 through March 1999), we conclude that the long-period variability of the water-vapor maser emission has a period of ∼11.5 years. We give arguments that this variability is mainly associated with the most compact group of maser spots, whose positions coincide with the position of the continuum source VLA 2.

Variation of spectral features in the ON2 water maser

Results are presented of the analysis of maser spectra in ON2, obtained with the RT-22 radio telescope at Pushchino during 1981–1996. The spectral features are analyzed and their time evolution examined. Anticorrelation between the fluxes of features with close radial velocities is found. A systematic displacement of the drifts sum of all features from 0.8 to during 1981–1988 and 1990–1996 is observed. In 1989 a fast jump of this parameter from -0.3 to took place. The quadratic sum of the drifts of the features always increased during a rise in maser activity. Possible causes of the observed phenomena are discussed.

Evolution of H2O maser emission in the direction of the semiregular variable RT Virginis during 1985-1996

We present a catalog of the 22 GHz H2 Om aser proles of the semiregular variable RT Vir. The observa- tions were made from 1985 to 1996 at the RT-22 radio telescope of the Radio Astronomical Station at Pushchino, Russia. Results obtained after the analysis of the inte- grated fluxes, the average spectra, the centroid velocity and the superposition of the spectra are reported. Anticorrelation of the integrated fluxes of two spectral intervals (VLSR 21 km s 1 ) was found. The characteristic time variation of the maser emission at each of these groups was about 5-6 years. This phe- nomenon may be explained by a variation of the outflow of the matter from the star. The outflow is weakly bipolar. We can suppose that in such a model the enhancement of the outflow occured alternately with a period of about 5-6 years. The anticorrelation of the integrated fluxes of two groups of maser features, located symmetrically relative to the star, may be a result of this alternation.

Time variations of the ON2 water maser spectrum during 1981-1995

Results of observations at 22.2 GHz of the water maser source ON2 carried out at the Pushchino RT-22 radio telescope during 1981-1995 are presented. The long-time regular observations of ON2 show that the time interval between the two high levels of the integrated H2 O flux density is more than 20 years. The flare component of the variability of total flux as well as strong flares of some features were not detected. The emission is concentrated, basically, in two spectrally separated groups of features. The observed anticorrelation of the fluxes of these groups was manifested only in the period of minimum activity of the H2 O maser. It seems that the transition of the maser takes place from the unsaturated state to a partly saturated one and vice versa. The variability of the maser emission has a global character for ON2 and may be caused by non-stationary physical processes at the early stages of stellar evolution.

Magnetic field value in the weak energy release region of the solar corona

Spectrographic data from observations of the polarized weak steplike (with relatively sharp growth t ∼ 3 sec and slow decay t ∼ 102 sec) solar continuum radioemission are analyzed below. The main results are found using a sweeping spectrograph in the 8–12 GHz frequency range (sweep rate 1 sample per second and frequency resolution 120 MHz) and using the RT-22 radio telescope at the Crimean Astrophysical Observatory (angular resolution 4′–6′). In a series of events at the leading edge of the continuum a narrow-band frequency drifting emission termed “blip-type” is found. The degree of continuum circular polarization (p<10%) is low compared to that of the narrow-band component (p≈20%). Both components of the aforementioned events should be radiating on the second harmonic of the local plasma frequency in the context of a plasma generating mechanism. Based on the model proposed and using the observed degree of circular polarization of each component, we can estimate the strength of the magnetic field within the area of the source and the width of the angular spectrum from the radiating plasma turbulence. The results of analysis of the real microwave events are given below.

Attenuation of radiation at wavelengths of 1.25 and 2.0 mm

The results of measurements of radiation attenuation at wavelengths of 1.25 and 2.0 mm in clouds, carried out in the Crimea, using the RT-22 radiotelescope are presented. This telescope has an antenna diameter of 22 m and is coupled to a Fabry Perot interferometer and a liquid-helium cooled n-type InSb detector.

Increasing the sensitivity of the RT-22 radiotelescope of the Crimean Astronomical Observatory (CAO) in the 3-cm range of wavelengths for a radiointer ferometer having a limiting angular resolution

Increasing the sensitivity of the RT-22 radiotelescope of the Crimean Astronomical Observatory (CAO) in the 3-cm range of wavelengths for a radiointer ferometer having a limiting angular resolution

Parameters of the antenna of the RT-22 radio telescope at the Crimean Astronomical Observatory at wavelengths of 3 and 1.35 cm

Parameters of the antenna of the RT-22 radio telescope at the Crimean Astronomical Observatory at wavelengths of 3 and 1.35 cm

Increasing the efficiency of the RT-22 radiotelescope at 8-mm wavelength

Increasing the efficiency of the RT-22 radiotelescope at 8-mm wavelength