Radioastronomical station Simeiz of laboratory of radioastronomy
of Crimean astrophysical observatory

Equipment

Low noise receivers at the X (3.6 cm) and S (13 cm) bands with a dual-frequency feed were installed at the prime focus of the antenna. The feed illuminates the main dish of the antenna over an angle of 140^o at a level of -10 db. The feed may receive both left and right circular polarization at the X band and either left or right circular polarization at the S band, although only one polarization can be recorded during observations.

The S and X band receivers are constructed using a superheterodyne scheme with FET high frequency amplifiers. A fronted directional coupler and FET amplifiers are cooled to 20 K with the help of a micro-cryogenic closed cycle system in order to reduce thermal noise. Focusing the system and measurements of system equivalent flux density (SEFD) are made by measuring the power pattern of the antenna from observations of the strongest radio sources Taurus-A, Virgo-A, Cas-A, and Cygnus-A before and after each observational session. Typical values of SEFD are 800 Jy at the X-band and 1200 Jy at the S-band. The system temperature is measured before each observation for diagnostic purposes and for scaling the phase calibration signal amplitudes.

The radio telescope operation is supported by the control system consisting of two encoders with an accuracy of positioning of 3 arcsec (rms), computers IBM PC, CAMAC, quartz time standard, electric engines and other equipment and software. Two engines with 20 kW power each provide the fast radio telescope motion and are used for a rapid change of the pointing or for radio telescope motion from one source to another. Another two 2 kW engines are used for slow tracking the source. The RT-22 is equipped by the hydrogen mazer frequency standard CH1-70 with a stability of 10^-14 over an interval from 1 to 24 hours and the Mark-IIIA recorder. The figures illustrating the most important elements of the RT-22 control system are the following:

The control system of the radio telescope provides the possibility to point the antenna and to track an observed source in two regimes: autonomous and automatic. Operator sets the targeted source coordinates using the computer keyboard when the system works in autonomous regime. All the modes of the radio telescope operation, namely, antenna motion, radiometer readings, and data recording, are given from the special host computer in automatic regime.

The radio telescope does not have a cover sheet (radome). Low frequencies equipment and recording system are located at the laboratory building in 30 m apart from the radio telescope.

The parameters of the 22-m radio telescope are the following:

Telescope	RT22
First single dish observation	1966
First VLBI observation	1969
Diameter	22 m
Surface tolerance (root mean square)	0.25 mm
Wavelength limit	2 mm
Feed System	Cassegrain System and Primary Focus
Focal length F	9.525 mm
Focal ratio F/D	0.43
Effective focal length for Cassegrain system	134.5 m
Mounting	Azimuth-Elevation
Pointing accuracy	10 arc sec
Maximum slewing rate	1.5 degree/sec
Maximum tracking rate	150 arcsec/sec
Working range in Azimuth	[-270, 270] degrees
Working range in Elevation	[     0,   85] degrees
SEFD at 92 cm wavelength	400
SEFD at 49 cm wavelength	420
SEFD at 18 cm wavelength	940
SEFD at 13 cm wavelength	800
SEFD at  6 cm wavelength	900
SEFD at 3.6 cm wavelength	1200
SEFD at 1.3 cm wavelength	700