The Qitai radio telescope

This study presents a general outline of the Qitai radio telescope(QTT) project.Qitai,the site of the telescope,is a county of Xinjiang Uygur Autonomous Region of China,located in the east Tianshan Mountains at an elevation of about 1800 m.The QTT is a fully steerable,Gregorian-type telescope with a standard parabolic main reflector of 110 m diameter.The QTT has adopted an umbrella support,homology-symmetric lightweight design.The main reflector is active so that the deformation caused by gravit...     

Comets at radio wavelengths

Comets are considered as the most primitive objects in the Solar System. Their composition provides information on the composition of the primitive solar nebula, 4.6 Gyr ago. The radio domain is a privileged tool to study the composition of cometary ices. Observations of the OH radical at 18 cm wavelength allow us to measure the water production rate. A wealth of molecules (and some of their isotopologues) coming from the sublimation of ices in the nucleus have been identified by observations in the millimetre and submillimetre domains. We present an historical review on radio observations of comets, focusing on the results from our group, and including recent observations with the Nançay radio telescope, the IRAM antennas, the Odin satellite, the Herschel space observatory, ALMA, and the MIRO instrument aboard the Rosetta space probe.     

Astronomy at radio frequencies

The radio astronomer requires a specialized combination of aerial and receiver to be able to detect, measure and map extra-terrestrial signals. The following article presents a brief account of the basic techniques employed.     

The guyed NIRFI radio telescope

Conclusions The experiment of planning, constructing, and operating the RTVS-12 radio telescope has demonstrated that it is possible in principle to use a prestressed guyed rod spatial structure for the construction of a fully steerable reflecting antenna.One of the main advantages of this antenna over other antennas of the same size is the light weight of the dish, 1.3 tons. As far as we know, a dish with the usual girder structure weighs 2–4 times as much (unfortunately, there is little data on small-diameter dishes, and moreover, different authors mean different things by the weight of the dish).The RTVS-12 radio telescope was created as an instrument for decameter wavelengths, that is, the dish was not designed to have a high surface accuracy. In operating the antenna, however, it became clear that it could operate at shorter wavelengths.The RTVS-12 antenna was a practical test of techniques for calculating similar structures; the accuracy of force calculations for a portable guyed system was determined and the basic shortcomings and omissions were made evident. The data obtained have enabled us to begin planning a guyed radio telescope with a dish 36 m in diameter, with a better perfected structural plan for the dish and the support-rotation structure.Scientific-Research Institute of Radiophysics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 22, No. 11, pp. 1293–1300, November, 1979.     

Regularization methods in radio interferometry

The problem of image retrieval in radio interferometry is a classical example of an ill-posed problem. In this paper, we consider a new approach to the radio-interferometric imaging based on regularization, which is computationally more flexible. A new type of a weighting function suitable for managing the interferometer antenna pattern is obtained. The regularization procedure was implemented in the VLBI-image processing software developed at the Astrospace Center of the Lebedev Physical Institute (ASC LPI). It is shown that the joint use of the developed regularization methods with traditional deconvolution algorithms such as CLEAN and self-calibration improve the quality of images of cosmic radio-emission sources. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 6, pp. 453–460, June 2007.     

The international scientific radio union

Dr. Reginald Smith-Rose, C.B.E., D.Sc., Ph.D., F.C.G.I., M.I.E.E., F.I.R.E., has been elected to succeed Dr. Lloyd Berkner of the U.S.A. as President of the International Scientific Radio Union (URSI). Previous holders of the office include the late Father Lejay of France and another British scientist, Sir Edward Appleton.