Artigos de revistas: "Radio telescopes"

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Li, Yuqiao. "State-of-art Facilities and Prospect of Radio Telescopes". Highlights in Science, Engineering and Technology 5 (7 de julho de 2022): 201–7. http://dx.doi.org/10.54097/hset.v5i.743.

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The radio telescopes play a crucial role in astrophysical observations; hence it is necessary to discuss about the significance, structure, and applications of radio telescope and analyse the difference between the state-of-art radio telescopes (FAST and SKA) based on present information. Specifically, the background and present conditions as well as the history of radio telescopes will be introduced initially. Subsequently, the significance of radio telescope will be explained, including structure and application of radio telescopes. Subsequently, the doubts on FAST and SKA and strengths of them will be clarified. Eventually, the problems and limitations about radio telescope and the future prospect will be discussed. Overall, these results shed light on offering suggestions for future development of galaxy and cosmology observations.

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Hong, Yiduo. "Working principle of the radio telescope and the study of the sun". Theoretical and Natural Science 12, n.º 1 (17 de novembro de 2023): 172–76. http://dx.doi.org/10.54254/2753-8818/12/20230461.

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Radio telescopes can help people observe celestial bodies far away from people, which is conducive for astronomers to observe and draw the trend of celestial transformations. The use of radio telescopes allows scholars to study and understand celestial bodies to a new height. At present, the more famous are the Webb Space Telescope in the United States, the Hubble Space Telescope and China's Tianyan. In the case of the eye of Heaven in Guizhou, China, the surface of the eye is covered by a metal layer one millimeter thick, so it can not withstand excessive pressure, and the maintenance personnel need to attach themselves to a giant helium balloon to reduce their weight, the whole process is so careful to ensure the safety of the precision instrument. So there are still some limitations in the development of radio telescopes. This paper will focus on the working principle of the radio telescope, the development of the radio telescope and techniques for observing the sun with radio telescopes, summarize the achievements of the radio telescope so far and the areas that need to be improved. To better understand radio telescopes.

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Song, Su. "Evolutions and Principles of Space and Radio Telescope". Highlights in Science, Engineering and Technology 72 (15 de dezembro de 2023): 47–52. http://dx.doi.org/10.54097/8r8fyx84.

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Contemporarily, various types of telescopes have been proposed as tools for cosmology observation. This study discusses main types of telescopes, i.e., space and radio telescopes people used to observe universe and gives deep description and comparison between them. Radio telescope is the telescope which can receive radio waves from the outer space and can detect waves in different wavelengths besides visible light. It has a long history, as radio telescope is built on Earth and relatively easier for people to make it, but the drawback is that radio telescope may be disturbed by nature conditions easily, even a small change in the strength of wind or the thickness of atmosphere can make a huge difference to the result. While space telescope is different. The first space telescope is Hubble Space Telescope, which is launched in 1990, thus the history of space telescope is relatively short. Compared with radio telescope, space telescope has its own advantage: since it works in space, changing nature conditions in Earth will not affect its precision, and some cancan work without the impact of infrared radiation of the Earth. However, the repair and maintenance cost are problems as it is difficult for people to go to space and fix the broken parts regularly. This paper can help people have a better understanding of these types of telescopes which are used frequently in observation for the universe.

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Wang, Yu, Haiyan Zhang, Jian Wang, Shijie Huang, Hao Hu e Cheng Yang. "A Software for RFI Analysis of Radio Environment around Radio Telescope". Universe 9, n.º 6 (8 de junho de 2023): 277. http://dx.doi.org/10.3390/universe9060277.

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Radio astronomy uses radio telescopes to detect very faint emissions from celestial objects. However, human-made radio frequency interference (RFI) is currently a common problem faced by most terrestrial radio telescopes, and it is getting worse with the development of the economy and technology. Therefore, it is essential to monitor and evaluate interference during the planning, construction, and operation stages of the radio telescope and protect the quiet radio environment around the radio astronomical site. In this paper, we present a software for an RFI analysis of the radio environment around the telescope. In this software, information has been collected, including the location of the site; the technical specifications, such as aperture and the frequency range of the radio telescopes; and the terrain around the site. The software and its modules are composed of telescope, geographic, and meteorological databases, and analysis modules of terrestrial and space-based RFI. Combined with the propagation characteristics of radio waves, we can analyze and evaluate RFI on the ground and in space around the radio telescope. The feasibility of the software has been proved by the experimental implementation of the propagation properties and RFI source estimation. With this software, efficient technical support can be expected for protecting the radio environment around the telescope, as well as improving site selection for planned radio astronomical facilities.

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Wu, Shengyin, Shouguan Wang, Yukuan Mao e Yan Su. "Trying to Enlarge the Sky Coverage of the FAST". International Astronomical Union Colloquium 182 (2001): 249–53. http://dx.doi.org/10.1017/s0252921100001068.

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AbstractThe proposed FAST project is a novel giant spherical radio telescope, with active elements which form a temporary paraboloid to track radio objects in the sky. Efforts have been made to extend the limited sky coverage that is a characteristic disadvantage of Arecibo-style radio telescopes. Three measures under investigation are introduced in this paper. The expected performance of the telescope is described, and a brief comparison is made with some of the largest existing radio telescopes.

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Wang, Jing-Sheng. "Newly Installed Radio and Optical Telescopes in China". Publications of the Astronomical Society of Australia 9, n.º 1 (1991): 60–61. http://dx.doi.org/10.1017/s1323358000024899.

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AbstractNew radio and optical telescopes installed in recent years in China are summarised. These include the 2.16-m optical telescope, the solar magnetic field telescope, the Miyun synthesis radio telescope, the 1.26-m infrared telescope (Beijing Astronomical Observatory), the 25-m radio telescope as the first station of China’s VLBI network, the 1.56-m astrometric telescope (Shanghai Observatory), and the 13.7-m millimetre wave radio telescope.

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Iyer, Aditya Arun, Gautham Manuru Prabhu, Tanay Gupta, Shrey Deshmukh e Rushit Rivankar. "Exploring Design Optimisation Techniques of a Radio Telescope Using Fixed Costing Constraints". Journal of Physics: Conference Series 2571, n.º 1 (1 de outubro de 2023): 012031. http://dx.doi.org/10.1088/1742-6596/2571/1/012031.

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Abstract Cost optimization is a common problem encountered in the design of telescopes. This paper comprehensively discusses various radio telescope designs worldwide, focusing on their design and utilities. It contextualizes the Pulsar data challenge and subsequently discusses and develops a mathematical model for designing radio telescopes. The model assumes a fixed-cost budget. This paper expands current ideas of modeling the system using figure-of-merit equations and optimizing them based on a fixed budget to obtain optimal and affordable radio telescope designs.

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Yan, Yuefei, Song Xue, Xinlan Hu, Peiyuan Lian, Qian Xu, Na Wang, Wulin Zhao, Yang Wu, Baoyan Duan e Congsi Wang. "Progress and Challenges in Electromechanical Coupling of Radio Telescopes". International Journal of Antennas and Propagation 2022 (22 de novembro de 2022): 1–21. http://dx.doi.org/10.1155/2022/4728303.

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Radio astronomy is a discipline of dynamics and wonders. The vast universe has many secrets to unravel. As one of the important facilities in this discipline, radio telescopes play a key role in collecting astronomical data and unraveling mysteries. With the demand of radio astronomy for a higher frequency, wider bandwidth, higher gain, and higher pointing accuracy, the aperture of the radio telescope is gradually increasing, and its electrical performance and structure have become tightly coupled. Therefore, how to ensure the stable and efficient operation of the telescope for the long-term operation has become the urgent demand for large aperture high-performance radio telescopes. Therefore, this paper firstly makes a comparison of the overall condition of large radio telescopes in nearly a decade that are both constructed and operated, including the progress of radio telescopes that are being constructed and the planning for construction. Then, systematically summarized the latest research progress of electromechanical coupling technology from 3 aspects of connotation and application of electromechanical coupling, and performance guarantee under slowly varying load and performance guarantee under rapidly varying load from the perspectives of design, manufacturing, and observation operating. Lastly, the future research direction of electromechanical coupling technology is pointed out according to the development trend of radio astronomy.

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Y. CH BISSA, Stevry, Ibnu Nurul Huda, Muhammad Bayu Saputra, Sofian Rizal, Ridlo W. Wibowo e Farahhati Mumtahana. "Development of artificial Earth satellite simulation software for future radio telescopes in Indonesia". Romanian Astronomical Journal 33, n.º 1-2 (12 de dezembro de 2023): 3–14. http://dx.doi.org/10.59277/roaj.2023.1-2.01.

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"In the near future, four radio telescopes will be installed in Indonesia. Besides the astronomical purposes, these telescopes are expected to support the ground station for tracking the Artificial Earth Satellites (AES). In this study, we focus on the development of AES simulation software, named AESSIMS, that can be used to aid Indonesian radio telescope engineers in tracking the AES. This software is interactive and web-based. It can track the AES position in real time as well as predict the position for the near future. This software provides information about when a satellite signal can be acquired and lost, which can be beneficial for radio telescopes to establish communication with the satellite. We visualize the use of this software by conducting a simulation of satellite tracking by Indonesian future radio telescopes. Three Indonesian satellites named LAPAN-A1/TUBSAT, LAPAN-A2/ORARI, and LAPAN-A3/IPB are considered in the simulation. This study demonstrates that AESSIMS simulation results for Indonesian satellites and radio telescopes are consistent with the results obtained from already existing satellite tracking simulation software."

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Yang, Guang Pu, Liang Dong, Le Sheng He, Fa Xin Shen, Bin Tian e Sheng Yang Li. "A New Platform for Radio Astronomy Science Education". Advances in Science and Technology 105 (abril de 2021): 179–83. http://dx.doi.org/10.4028/www.scientific.net/ast.105.179.

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Radio astronomy telescope can get information from invisible universe by receiving electromagnetic waves. Difference from optical telescopes, there exists many difficulties for making the public understanding the radio astronomy phenomenon. In this paper, we will introduce a new platform for radio astronomy science popularization education in order to help public know radio telescope and radio astronomy. The platform consists of a 0.8meter parabolic antenna, a wide bandwidth low noise amplifier (LNA) and a Software Defined Radio (SDR) terminal. Based on SDR terminal which covers the band from 70MHz to 6GHz, we can get some strong emissions such as the Neutral hydrogen, solar radio bursts and so on in this band. People can carry out many radio astronomy experiments focusing on science popularization by this platform. This new science education tool can interest high school students in science and technology, also students can understand how radio telescopes works.

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Kellermann, K. I. "New Radio Telescopes". Highlights of Astronomy 7 (1986): 879–88. http://dx.doi.org/10.1017/s1539299600007413.

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AbstractNearly all of the exciting discoveries in radio astronomy have come from new instruments or techniques which have provided new frequencies, high sensitivity, higher spatial or time resolution, or improved image quality. Since the last General Assembly a number of major new radio telescopes have been completed while construction of others have only just begun. At the same time telescopes of the more distant future are still in the conceptual stage. This paper summarizes a full-day meeting of Commission 40 on recently completed radio telescopes, new radio telescopes now under construction, and radio telescopes of the future.

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Kawaguchi, Noriyuki. "Japanese radio telescopes". Advances in Space Research 11, n.º 2 (janeiro de 1991): 407–9. http://dx.doi.org/10.1016/0273-1177(91)90525-o.

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Wei, Shanxiang, Deqing Kong, Binlan Wang, Lianbo Fu, Wenrong Xiao, Zongming Yin, Yongxiang Li e Zhouzhou Xiao. "Estimation of Pointing Errors of Large Radio Telescopes under Solar Radiation Based on Digital Twin". Symmetry 16, n.º 6 (29 de maio de 2024): 668. http://dx.doi.org/10.3390/sym16060668.

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The pointing accuracy of large radio telescopes is affected by antenna structure errors, installation errors, servo errors, gravity, and varying environmental factors. Although an on-line pointing model had been developed in the past for several large radio telescopes to correct these effects, it is also valuable to explore new ways to correct these effects. Therefore, in order to estimate the dynamic pointing error of large radio telescopes under solar radiation, a new way based on digital twin (DT) is used in this paper. Digital models of the Wuqing 70-m radio telescope (WRT70) are created based on the DT operational framework. Finally, the reliability of the WRT70’s DT system is verified, and the dynamic pointing error of WRT70 (staying at the position of the elevation angle of 90° and the azimuth angle of 180°) on two sunny days in different seasons is estimated by the created DT system. The research results show that the pointing error of large radio telescopes under solar radiation fluctuates greatly and the seasonal differences are very striking. The maximum elevation pointing error of WRT70 under solar radiation around the winter solstice is over 40 arcsec, which is equal to 4/11 of the beam width for WRT70 operating at 8 GHz. In this paper, it is feasible to estimate the time-varying pointing errors of large radio telescopes at rest under solar radiation by constructing a DT system, but it is not effective to estimate the dynamic pointing errors of large radio telescopes in operation. It is expected to establish a dynamic pointing error model and calibrate the dynamic pointing errors of large radio telescopes in operation by DT technology in the future.

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Cenacchi, Elena, A. Kraus e K. H. Mack. "Deriving AGN properties from circular and linear radio polarimetry". Proceedings of the International Astronomical Union 4, S259 (novembro de 2008): 561–62. http://dx.doi.org/10.1017/s1743921309031330.

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AbstractWe report multi-frequency circular polarization measurements for the radio source 0056-00 taken at the Effelsberg 100-m radio telescope. The data reduction is based on a new calibration procedure that allows the contemporary measurement of the four Stokes parameters with single-dish radio telescopes.

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Buch, Kaushal D., Shruti Bhatporia, Yashwant Gupta, Swapnil Nalawade, Aditya Chowdhury, Kishor Naik, Kshitij Aggarwal e B. Ajithkumar. "Towards Real-Time Impulsive RFI Mitigation for Radio Telescopes". Journal of Astronomical Instrumentation 05, n.º 04 (dezembro de 2016): 1641018. http://dx.doi.org/10.1142/s225117171641018x.

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Radio Frequency Interference (RFI) is a growing concern for contemporary radio telescopes. This paper describes techniques for real-time threshold-based detection and filtering of broadband and narrowband RFI for the correlator and beamformer chains of a telescope back-end, with specific applications to the upgraded Giant Meterwave Radio Telescope (uGMRT). The Median Absolute Deviation (MAD) estimator is used for robust estimation of dispersion of the received signal in temporal and spectral domains. Results from the tests carried out for the GMRT wide-band backend (GWB) using this technique show 10 dB improvement in the signal-to-noise ratio. MAD-based estimation and filtering was also found to be useful for filtering beamformer data. The RFI filtering technique demonstrated in this paper will find applications in other radio telescopes as well as receivers for digital communication and passive radiometry.

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Swarup, G., e C. R. Subramanya. "Preserving Radio Astronomy in Developing Nations". Symposium - International Astronomical Union 196 (2001): 270. http://dx.doi.org/10.1017/s0074180900164198.

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Due to the very weak nature of signals from cosmic radio sources, the sensitivity of a radio telescope and receiver is about 40–60 dB higher than those of communications receivers. Hence, radio telescopes are generally located in relatively radio-quiet locations and operate in frequency bands that are protected against radio interference through frequency planning by national governments. Taking advantage of the much lower degree of radio interference in developing countries and the relatively labour-intensive nature of metre-wave radio telescopes, several such radio telescopes have been built and are planned in Argentina, Brazil, China, India, Mauritius and South Africa. Radio telescopes operating at cm-wavelengths are also planned in Egypt and Mexico.A particularly severe problem arises for the radio astronomy service and other passive services below 2 GHz from the possibility of unacceptable emissions from satellites in unwanted bands (out-of-band and spurious emissions), due to the specific modulation schemes used in satellite transmitters. It is noted that this can be circumvented within the existing technologies if the satellite transmitters employ suitable bit-shaping or filtering techniques or use modulation schemes like Gaussian-filtered Minimum-Shift Keying (GMSK) which produce very little out-of-band emission. Although radio astronomy started in the western world at low frequencies, much low frequency radio astronomy is now planned or operational in developing countries. In order to protect the interests of these and other passive services within developing nations, it is important that suitable regulations be recommended to UNISPACE-III to provide appropriate protection.

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Sitompul, Peberlin Parulian, Pakhrur Razi, Timbul Manik, Mario Batubara, Musthofa Lathif, Farahhati Mumtahana, Rizal Suryana et al. "A Study for a Radio Telescope in Indonesia: Parabolic Design, Simulation of a Horn Antenna, and Radio Frequency Survey in Frequency of 0.045–18 GHz". Aerospace 11, n.º 1 (4 de janeiro de 2024): 52. http://dx.doi.org/10.3390/aerospace11010052.

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After years of preparation, the Indonesia National Observatory, located in Mount Timau, Kupang Regency, is currently in the completion stage of research in astronomy and astrophysics and related subjects. An optic telescope with a 3.8 m diameter is expected to receive its first light in mid-2024. A feasibility study for Indonesia’s radio telescopes and networks is in progress. A single-dish parabolic radio antenna with a diameter of 20 m is proposed to work in a frequency range of 1–50 GHz. An array dipole antenna with an area of 100 m × 100 m will also be installed at a 70–350 MHz frequency. A feasibility study about system design is in progress, and a radio frequency interference (RFI) survey has been underway since 2014. In this paper, we described the design of radio telescopes such as parabolic reflectors, horn antenna, and the radio frequency interference (RFI) in the surrounding area of the National Observatory, covering the frequency band from 45 MHz to 18 GHz. The frequencies in 45–85 MHz and 120–360 MHz intervals are still relatively quiet and suitable for developing radio telescopes. The selected higher frequency of 1.4 GHz for a neutral hydrogen (HI) spectral line, 6.6 GHz for a methanol (CH3OH) spectral line, and 8.6 GHz for a helium (3 He+) spectral line is still relatively quiet and suitable for the development of radio telescopes.

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Chibueze, James O. "Maser Science with the African VLBI Network and MeerKAT". Proceedings of the International Astronomical Union 18, S380 (dezembro de 2022): 452–56. http://dx.doi.org/10.1017/s1743921323003149.

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AbstractThe African VLBI Network (AVN) is slowly becoming a reality. A couple of successful fringe test observations have been conducted even as single-dish maser monitoring observations constitute the main activity on the telescopes (HartRAO 26 m and Ghana 32 m). Some of the recent observational results from the AVN telescopes includes detection of velocity drifts in masers. Although MeerKAT is largely designed for high sensitivity continuum and HI science, its bands cover some masers and is already making impressive discoveries. The need to grow the critical mass of radio astronomers in the African continent persists. The NWU 4-dish interferometer, the Nigeria 3.7 m radio telescope and the African Millimeter Telescope (AMT) are some of the initiatives that will significantly improve the statistics of radio astronomers in Africa.

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Lu, Zhiyi. "Analysis of the Principle and State-of-art Applications of Astronomical Telescope". Highlights in Science, Engineering and Technology 72 (15 de dezembro de 2023): 83–89. http://dx.doi.org/10.54097/4kna8f33.

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Astronomical telescopes have been instrumental in enhancing our comprehension of the cosmos since ancient eras. This study explores these remarkable instruments' principles and state-of-art applications, tracing their development from early refracting telescopes to modern space and ground-based telescopes. The primary focus is to analyze the imaging principles of optical and radio telescopes and showcase their significance in capturing high-resolution observations of celestial objects. It also highlights recent achievements made by advanced telescopes, including the James Webb Space Telescope and the Event Horizon Telescope, which have provided unprecedented clarity and insights into distant galaxies, exoplanets, and supermassive black holes. This research presents breakthrough achievements made by advanced telescopes such as the James Webb Space Telescope and the Event Horizon Telescope in revealing distant galaxies, exoplanets, and supermassive black holes. Despite the limitations in astronomical telescope research, such as errors, atmospheric interference, and high costs, the paper emphasizes a promising future. Through technological advancements, international collaboration, and cost-effective space telescopes, astronomical research is expected to make significant progress. In summary, these results provide a comprehensive analysis of astronomical telescopes, enriches the frontiers of astronomy, underscores the importance of international cooperation, and offer essential guidance for the future development of astronomy.

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Mulumba, Dorcus. "Design and development of a two-dish interferometer". Proceedings of the International Astronomical Union 15, S356 (outubro de 2019): 408. http://dx.doi.org/10.1017/s1743921320003622.

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AbstractThe angular resolution and the sensitivity of a parabolic dish telescope increase with the diameter of its aperture at a given frequency. This implies that as the telescope gets larger, its resolution becomes better. However, constructing telescopes of ever increasing size is prohibitive for both technical and financial reasons. This problem is solved by using an interferometer which consists of two or more separate telescopes that combine their signals offering a resolution equivalent to the largest separation distance between the telescopes. In this work, the electric field variations from two telescopes will be obtained. The voltage signals from the two telescopes will be coherently combined in order to derive the structure of the target source of radio emission. This combination will be done by a cross-correlator, which multiplies and averages the voltage outputs V1 and V2 of the two dishes. A major challenge to be addressed in this work is to design an instrument capable of making professional-type radio astronomy measurement in a local interference environment. In this regard, the investigative part of this work will verify whether it is possible to achieve a high sensitivity enough to detect some cosmic sources where the presence of man-made interference and cost adversely influences the system. The design of an interferometer will be presented and implemented. It may also serve as a demonstrator for engineering students to gain a working knowledge of radio interferometry.

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Liu, Xuan, Junhong Deng, King Fai Li, Mingke Jin, Yutao Tang, Xuecai Zhang, Xing Cheng, Hong Wang, Wei Liu e Guixin Li. "Optical telescope with Cassegrain metasurfaces". Nanophotonics 9, n.º 10 (10 de abril de 2020): 3263–69. http://dx.doi.org/10.1515/nanoph-2020-0012.

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AbstractThe Cassegrain telescope, made of a concave primary mirror and a convex secondary mirror, is widely utilized for modern astronomical observation. However, the existence of curved mirrors inevitably results in bulky configurations. Here, we propose a new design of the miniaturized Cassegrain telescope by replacing the curved mirrors with planar reflective metasurfaces. The focusing and imaging properties of the Cassegrain metasurface telescopes are experimentally verified for circularly polarized incident light at near infrared wavelengths. The concept of the metasurface telescopes can be employed for applications in telescopes working at infrared, Terahertz, and microwave and even radio frequencies.

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Jallod, Uday E., Hareth S. Mahdi e Kamal M. Abood. "Simulation of Small Radio Telescope Antenna Parameters at Frequency of 1.42 GHz". Iraqi Journal of Physics (IJP) 20, n.º 1 (1 de março de 2022): 37–47. http://dx.doi.org/10.30723/ijp.v20i1.726.

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The paper presents an overview of theoretical aspects of small radio telescope antenna parameters. The basic parameters include antenna beamwidth, antenna gain, aperture efficiency, and antenna temperature. These parameters should be carefully studied since they have vital effects on astronomical radio observations. The simulations of antenna parameters were carried out to assess the capability and the efficiency of small radio telescopes to observe a point source at a specific frequency. Two-dimensional numerical simulations of a uniform circular aperture antenna are implemented at different radii. The small diameter values are chosen to be varied between (1-10) m. This study focuses on a small radio telescope with a diameter of 3 m since this telescope is very common in the world. The simulated results of this study illustrated that the power pattern of a 3 m antenna has a half-power beamwidth of approximately 5 degrees. Also, the maximum peak antenna temperature is estimated to be more than 3000 K. All of these results were in good agreement with observations of the neutral hydrogen spectral line at the frequency of 1.42 GHz using a small radio telescope.

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Levanda, Ronny, e Amir Leshem. "Synthetic aperture radio telescopes". IEEE Signal Processing Magazine 27, n.º 1 (janeiro de 2010): 14–29. http://dx.doi.org/10.1109/msp.2009.934719.

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Sobirin, Farhan Fatwa, Satia Nugraha, Fauzia Haz e Peberlin Sitompul. "Study of Cassegrain-type antenna for radio telescope". Journal of Physics: Conference Series 2214, n.º 1 (1 de fevereiro de 2022): 012028. http://dx.doi.org/10.1088/1742-6596/2214/1/012028.

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Abstract There are many critical parameters in the design of a radio telescope, such as antenna gain and antenna resolution. In telecommunications, radar, and radio telescopes, an antenna is a very important component. There are many designs of the antenna, such as dipole array and parabolic antenna. Parabolic antennas also have many sub-reflector and antenna methods that control the radio wave, such as the Cassegrain type. A Cassegrain-type antenna is a parabolic antenna in which the feed antenna is mounted at or behind the surface of the main parabolic reflector dish. For the transmitter system, the beam of radio waves from the feed antenna illuminates the secondary reflector (sub-reflector), which reflects it back to the main reflector dish and then forward to space. The Cassegrain design is widely used in parabolic antennas, for large antennas in satellite ground stations, communication satellites, and radio telescopes. In this paper discusses the design of a Cassegrain-type antenna for radio telescope, basic calculation, diameter size of the main reflector of 20 meters, the diameter size of sub-reflector of 2.5 meters, and frequency of 22 GHz and 43 GHz.

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Dewdney, P. E., e T. L. Landecker. "The Proposed Radio Schmidt Telescope: The technical challenges". International Astronomical Union Colloquium 131 (1991): 415–19. http://dx.doi.org/10.1017/s0252921100013750.

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AbstractThe concept of the Radio Schmidt Telescope is designed to fill a scientific requirement for a radio telescope which is very sensitive to diffuse, extended emission, but has much higher resolution than singleantenna telescopes. This telescope undertakes to utilize a new region of “parameter space” in the aperture synthesis technique. The emphasis of this article is on a process leading to the best implementation of the concept at reasonable cost while satisfying all the scientific objectives.

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Chen, Yufan (Jerry). "Understanding Black Hole Imaging Based on Very Large Baseline Interferometry (VLBI)". Applied Science and Innovative Research 6, n.º 3 (15 de junho de 2022): p21. http://dx.doi.org/10.22158/asir.v6n3p21.

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In 2019, the Event Horizon Telescope made history when it captured the first known image of a blackhole. The black hole, situated in the center of the Messier 87 galaxy, is more than 55 million light-years away from earth, and was only able to be captured using Very Large Baseline Interferometry (VLBI) technology and the computational imaging technologies integrated into the Event Horizon Telescope array (The Event Horizon Telescope Collaboration, 2019). Astronomical image processing and interferometry requires the collection of radio waves using a radio telescope and analyzing that data with software. VLBI collects signals with multiple telescopes simultaneously, and the resulting data can be reduced and analyzed as data collected by a telescope with the diameter equal to the largest distance between the telescopes, thus is capable of producing an image with higher angular resolution and capturing objects further away from earth. However, due to the distance between the VLBI telescopes, algorithms are needed to fill in the hole within the collected data and reduce atmospheric noise and delays in signals (Very Long Baseline Array (VLBA)). We conduct an in depth review of the algorithm and VLBI as a whole in this paper, and hope to use our findings to further push the development of this great technology.

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Kardashev, N. S., e V. I. Slysh. "The RADIOASTRON Project". Symposium - International Astronomical Union 129 (1988): 433–40. http://dx.doi.org/10.1017/s0074180900135211.

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The RADIOASTRON mission (Andreyanov et al. 1986) is designed to achieve angular resolutions as fine as 6 microarcsec and will be used to study radio sources with very high brightness temperature. It will form an orbiting radio interferometer between a satellite radio telescope 10 m in diameter and several large ground-based radio telescopes. The orbit of the satellite makes it possible to have baselines from several thousands to 80,000 km. The satellite will be equipped with four dual polarization receivers at 327, 1665, 4830, and 22235 MHz, with local oscillators phase-locked to a ground-based hydrogen maser frequency standard via an S-band microwave link. The IF signals from the receivers will be transmitted to the ground by an X-band high data rate link and recorded on magnetic tape in the VLBA format. Participation of large radio telescopes from many countries is envisaged and encouraged.

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Peng, B., e R. Nan. "Kilometer-Square Area Radio Synthesis Telescope Karst Project". Symposium - International Astronomical Union 179 (1998): 93–94. http://dx.doi.org/10.1017/s0074180900128268.

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One way to realize the Large radio Telescope with a collecting area approaching one square kilometer, continuously covering a frequency range between 200 MHz and 2 GHz, is to construct a passive spherical reflector array of about 30 individual unit telescopes, each ∼ 300 m diameter(Butcher 1995). Valleys amid the hills of southwest China would be ideal for such LT concept. We refer to this effort as the Kilometer-square Area Radio Synthesis Telescope project. Site surveying and Radio Interference monitoring looks promising. Engineering considerations are summarized.

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Ruf, K., E. Fürst, K. Grypstra, J. Neidhöfer e M. Schumacher. "Response of the Effelsberg 100m radio telescope to signals in the near-field at 24 GHz". Advances in Radio Science 1 (5 de maio de 2003): 329–33. http://dx.doi.org/10.5194/ars-1-329-2003.

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Abstract. Short range radar (SRR) for cars has been proposed to operate over 5 GHz of bandwidth at the 24 GHz ISM band. To estimate the level of interference from these devices on radio telescopes, the near-field antenna pattern has to be known. We report on new measurements with the Effelsberg 100 m radio telescope. These measurements were performed with a transmitter set up at a distance of 1.7 km from the telescope. The strength of the signal picked up by the telescope sidelobes shows that the proposed SRR would interfere with sensitive radio astronomical observations.

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30

Harnett, J. I., R. F. Haynes, R. Wielebinski e U. Klein. "Radio Polarization Studies of Some Southern Galaxies". Symposium - International Astronomical Union 140 (1990): 225–26. http://dx.doi.org/10.1017/s0074180900190059.

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We have begun a long-range project to study southern galaxies using the radio telescopes at Parkes and Molonglo, the Siding Spring optical facilities and soon, the Australia Telescope. Here we present the results of polarization mapping at two wavelengths of the galaxies NGC 55, 253,4945, M 83 and the Circinus Galaxy.

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31

Altunin, V. "Protecting Space-Based Radio Astronomy". Symposium - International Astronomical Union 196 (2001): 324–34. http://dx.doi.org/10.1017/s0074180900164319.

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This paper outlines some of the radio frequency interference issues related to radio astronomy performed with space-based radio telescopes. Radio frequency interference that threatens radio astronomy observations from the surface of Earth will also degrade observations with space-based radio telescopes. However, any resulting interference could be different than for ground-based telescopes due to several factors. Space radio astronomy observations significantly enhance studies in different areas of astronomy. Several space radio astronomy experiments for studies in low-frequency radio astronomy, space VLBI, the cosmic microwave background and the submillimetre wavelengths have flown already. The first results from these missions have provided significant breakthroughs in our understanding of the nature of celestial radio radiation. Radio astronomers plan to deploy more radio telescopes in Earth orbit, in the vicinity of the L2 Sun-Earth Lagrangian point, and, in the more distant future, in the shielded zone of the Moon.

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Ekers, R. D. "Review of Linked Array Instruments". Highlights of Astronomy 8 (1989): 551–52. http://dx.doi.org/10.1017/s1539299600008297.

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At cm wavelengths aperture synthesis radio-telescopes (arrays of linked antennas which synthesize an image of the sky with high angular resolution) are now becoming the dominant astronomical research tool. Major new facilities such as the VLA are in full operation, others such as the Australia Telescope are nearing completion and a number of telescopes designed to form images in real time have been converted to operate in the aperture synthesis mode (e.g. MOST, Bologna Cross). See Napier et al. (1983) for a review of modern synthesis telescopes. The high resolution, sensitivity and freedom from confusion have led the aperture synthesis telescopes into very diverse astronomical applications.

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Maeda, Koitiro, e Noritaka Tokimasa. "Small Radio Telescopes for Education". Transactions of the International Astronomical Union 24, n.º 3 (2001): 307–11. http://dx.doi.org/10.1017/s0251107x00000985.

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AbstractWe present small radio telescopes consisting of commercial instruments for satellite TV reception. With these radio telescopes we can observe the 12 GHz emissions from the quiet sun and solar flares. Since microwaves occurring in our environment, e.g., those from a building and a fluorescent lamp, are also detectable, such radio telescopes are useful not only for radio astronomy education but also for physics education.

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Konovalenko, O. O., V. V. Zakharenko, L. M. Lytvynenko, O. M. Ulyanov, M. A. Sidorchuk, S. V. Stepkin, V. A. Shepelev et al. "THE FOUNDER OF THE DECAMETER RADIO ASTRONOMY IN UKRAINE ACADEMICIAN OF NAS OF UKRAINE SEMEN YAKOVYCH BRAUDE IS 110 YEARS OLD: HISTORY OF CREATION AND DEVELOPMENT OF THE NATIONAL EXPERIMENTAL BASE FOR THE LAST HALF CENTURY". Radio physics and radio astronomy 26, n.º 1 (3 de março de 2021): 5–73. http://dx.doi.org/10.15407/rpra26.01.005.

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Purpose: A historical review of the experimental baselopment of low-frequency radio astronomy in Ukraine, its foundation half a century ago by an outstanding scientist S.Ya. Braude to the current state. Design/methodology/approach: The constant progress of electronic, computer and digital technologies, information and telecommunication technologies, theory and practice of antenna and receiving systems design, which introduction enriched the hardware and methodological ideology of construction and usage of the UTR-2, URAN, and GURT radio telescopes, have been used. Findings: The worldwide most effective national experimental radio astronomy means, the UTR-2, URAN, and GURT decameter-meter wave radiotelescopes, have been created and improved. The best combination of the systems main parameters: sensitivity; frequency band; spatial, frequency and temporal resolutions; noise immunity; uniformity of amplitude-frequency and space-frequency characteristics and multifunctionality has been provided. Conclusions: For the half a century of radio astronomical scientific and technical at the Institute of Radio Astronomy of NAS of Ukraine, the high astrophysical informativeness of the low-frequency radio astronomy and the possibility of creating a highly efficient experimental base – giant radio telescopes of decameter-meter wavebands have been proved. Today, the Ukrainian radio telescopes are well known and recognized world-wide being indispensable and most in demand by the scientific community. The founder of the decameter radio astronomy in Ukraine, the eminent scientist Semen Yakovych Braude was not mistaken when he decided to start radio astronomical explorations. The memory of him will always remain in the minds and hearts of many generations. Key words: low-frequency radio astronomy; radio telescope; phase shifter; antenna amplifier; digital signal recorder; effective area; sensitivity; resolution; noise immunity

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Van Breugel, W. J. M. "HST and KECK Observations of High Redshift Radio Galaxies". Symposium - International Astronomical Union 175 (1996): 577–80. http://dx.doi.org/10.1017/s0074180900081900.

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Together with several of my colleagues I have embarked on a comprehensive program to study the radio–aligned restframe UV structures in high redshift radio galaxies (HzRGs) using some of the world's premier optical telescopes: the Hubble Space Telescope for high spatial resolution imaging, and the Keck 10m telescope for high S/N spectropolarimetry. I will discuss some of our latest results from these observations which elucidate, and at the same time obscure, our evolving understanding of HzRGs.

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36

Mumtahana, Farahhati, Ibnu Nurul Huda, Miftahul Husna, Timbul Manik, Peberlin Sitompul e Mario Batubara. "The potential use of the 20-meter radio telescope planned at the Timau National Observatory". Romanian Astronomical Journal 33, n.º 1-2 (12 de dezembro de 2023): 57–65. http://dx.doi.org/10.59277/roaj.2023.1-2.04.

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"The importance of radio telescopes for astronomy, geodesy, and other disciplines has been demonstrated by the growing number of radio telescopes worldwide, including in South-East Asia. Timau National Observatory has also considered a radiotelescope development program, which is expected to contribute both on a national and global scale. The diameter for the single dish is planned to be around 20-meter with a frequency range of 1-50 GHz. This paper outlines potential research for the planned radio telescope as a single dish as well as a part of future interferometer/VLBI collaboration. We collected several studies conducted with single antenna with a diameter of around 20-meter as a comparison to study its potential use as a single dish. As it is also essential to consider using an interferometer network, we also examined its capability as a part of VLBI, including the UV coverage and object simulation. Finally, it can be concluded that many studies can be conducted using the 20-m radio telescope as a single dish. Its location slightly below the equator can also play an important role in completing the global VLBI network."

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Kumagal, J. "Space mountain [submillimeter radio telescopes]". IEEE Spectrum 42, n.º 12 (dezembro de 2005): 12–14. http://dx.doi.org/10.1109/mspec.2005.1549770.

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Rowan-Robinson, Michael. "The Invisible Universe". Culture and Cosmos 16, n.º 1 and 2 (outubro de 2012): 255–59. http://dx.doi.org/10.46472/cc.001216.0241.

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With our own eyes we can see the night sky of the stars, planets and the Milky Way, the arena of pre-telescopic astronomy. Modern optical telescopes have opened up the universe of galaxies and we are familiar with the superb images of the Hubble Space Telescope. But with the invisible wavelengths of radio, infrared and X-ray, a very different universe comes into view. The astronomy of the invisible wavelengths was inaugurated by William Herschel in 1800 but developed very slowly over the next 160 years. The past fifty years have seen an explosion in our understanding of this strange world.

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Rowan-Robinson, Michael. "The Invisible Universe". Culture and Cosmos 16, n.º 0102 (outubro de 2012): 255–59. http://dx.doi.org/10.46472/cc.01216.0241.

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With our own eyes we can see the night sky of the stars, planets and the Milky Way, the arena of pre-telescopic astronomy. Modern optical telescopes have opened up the universe of galaxies and we are familiar with the superb images of the Hubble Space Telescope. But with the invisible wavelengths of radio, infrared and X-ray, a very different universe comes into view. The astronomy of the invisible wavelengths was inaugurated by William Herschel in 1800 but developed very slowly over the next 160 years. The past fifty years have seen an explosion in our understanding of this strange world.

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40

Myers, Frederick Shaw. "Radio Telescopes: Japan leads radio astronomers into space". Physics World 10, n.º 3 (março de 1997): 8. http://dx.doi.org/10.1088/2058-7058/10/3/7.

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Kulkarni, V. K., e S. Ananthakrishnan. "327 MHz Observations of 3C 84, 3C 120 and 1148-001". Symposium - International Astronomical Union 129 (1988): 121–22. http://dx.doi.org/10.1017/s0074180900134217.

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We have made VLBI observations of a mixed sample of bright galaxies and quasars at 327 MHz using the Ooty Radio Telescope in India and the telescopes at Jodrell Bank, Westerbork, Torun, and Crimea in December 1983 and March 1986. MK II recording was used and the data were processed at MPI, Bonn. The preliminary results of the 1983 analysis (Ananthakrishnan and Kulkarni 1986) showed most of the nearby galaxies to be resolved over the longest baselines of 8 million wavelengths. The only seyfert galaxies for which good S/N ratio was available at the longest baselines were 3C84 and 3C120. Although UV coverage was poor we attempted to make maps of these objects. The radio source 1148-001 was used for gain calibration of the telescopes.

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42

Sanidas, S., M. Caleb, L. Driessen, V. Morello, K. Rajwade e B. W. Stappers. "MeerTRAP: A pulsar and fast transients survey with MeerKAT". Proceedings of the International Astronomical Union 13, S337 (setembro de 2017): 406–7. http://dx.doi.org/10.1017/s1743921317009310.

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AbstractWe present a brief overview of MeerTRAP, a real-time, fully commensal survey for pulsars and fast transients with the MeerKAT radio telescope in South Africa. MeerTRAP will combine the excellent sensitivity of MeerKAT with an unprecedented amount of on-sky time in order to significantly extend the parameter space covered by similar, previous or ongoing, surveys with other radio telescopes. Here, we will give a brief overview of the project.

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43

Bean, Ben, Sanjay Bhatnagar, Sandra Castro, Jennifer Donovan Meyer, Bjorn Emonts, Enrique Garcia, Robert Garwood et al. "CASA, Common Astronomy Software Applications for Radio Astronomy". Publications of the Astronomical Society of the Pacific 134, n.º 1041 (1 de novembro de 2022): 114501. http://dx.doi.org/10.1088/1538-3873/ac9642.

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Abstract CASA, the Common Astronomy Software Applications, is the primary data processing software for the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA), and is frequently used also for other radio telescopes. The CASA software can handle data from single-dish, aperture-synthesis, and Very Long Baseline Interferometery (VLBI) telescopes. One of its core functionalities is to support the calibration and imaging pipelines for ALMA, VLA, VLA Sky Survey, and the Nobeyama 45 m telescope. This paper presents a high-level overview of the basic structure of the CASA software, as well as procedures for calibrating and imaging astronomical radio data in CASA. CASA is being developed by an international consortium of scientists and software engineers based at the National Radio Astronomy Observatory (NRAO), the European Southern Observatory, the National Astronomical Observatory of Japan, and the Joint Institute for VLBI European Research Infrastructure Consortium (JIV-ERIC), under the guidance of NRAO.

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44

Cordes, J. M. "New Radio Science Facilities for Compact Objects". Symposium - International Astronomical Union 218 (2004): 113–20. http://dx.doi.org/10.1017/s0074180900180738.

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In a throwback to the early days in radio astronomy, new concepts for radio telescopes are being considered as next-generation facilities. The Low-Frequency Array (LOFAR) and the Square-Kilometer Array (SKA) are two particular projects that will incorporate innovations in hardware and software. Along the way to these projects, major surveys for pulsars and transients and/or follow-up pulsar timing observations will be conducted with the ALFA multibeam system at Arecibo, the Allen Telescope Array (ATA), the Extended VLA (EVLA) and with SKA prototype systems that include the European MBRACE project (Multibeam Radio Astronomy Concept Experiment) and China's FAST (500m Aperture Spherical Telescope). These projects are discussed here in the context of anticipated science drivers.

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Volvach, Alexander, Olga Gopasyuk e Inna Yakubovskaya. "The Sun Service KRIM - diagnostic complex of solar activity". ITM Web of Conferences 30 (2019): 15003. http://dx.doi.org/10.1051/itmconf/20193015003.

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The radio astronomical diagnostic complex of solar activity, created on the basis of the radio telescope RT-22 and three small radiotelescopes united in the Sun Service KRIM located in coordinates longitude 33° 59' 30" latitude 44° 23' 52", conducts simultaneous observations in the wavelength range from 8 mm to 1.2 m in the monitoring mode and alerts. The Sun Service KRIM registered a series of strong outbreaks in the Sun in September 2017, when it was at a minimum of its activity. The information obtained by radio telescopes correlates well with data from other terrestrial and satellite observatories such as RSTN and GOES. Correlation coefficients are calculated and scattering diagrams for X-ray class flares X9.3 and X2.2 are constructed. The information from the radio telescopes of the Sun Service KRIM allows them to be used for daily monitoring of solar activity, further processing of data obtained in the course of scientific research, short-term forecast of space weather and analysis of its infuence on the Earth.

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Bezrukovs, D. "The Influence of Wind Turbines on Radio Astronomical Observations in Irbene". Latvian Journal of Physics and Technical Sciences 53, n.º 2 (1 de abril de 2016): 68–74. http://dx.doi.org/10.1515/lpts-2016-0015.

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Abstract The reflection and diffraction of external communication and navigational transmitters from tall constructions and moving blades of wind turbines produce some short-pulse additional electromagnetic interference strong enough to fully disturb radio astronomical observations. The problem of short-pulse electromagnetic interference is distinctive to all radio telescopes surrounded by wind turbines. This problem became significant for Ventspils International Radio Astronomy Centre (VIRAC) after new wind park “Platene” of Winergy Ltd. was built in 2012 and radio telescopes RT-16 and RT-32 renovated and equipped with cryogenic high sensitive receivers. The paper deals with the analysis and evaluation of intensities and probabilities of short-pulse interferences produced by wind park “Platene” and its possible impact on radio astronomical observations at VIRAC radio telescopes.

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Zakharov, A. F. "Astrometric microlensing with the RadioAstron space mission". Proceedings of the International Astronomical Union 3, S248 (outubro de 2007): 387–90. http://dx.doi.org/10.1017/s1743921308019625.

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AbstractAccording to a revised schedule of the Russian Space Agency, in October 2008 the 10 m space telescope RadioAstron will be launched in a high eccentric orbit around the Earth. Acting together with ground based radio telescopes, the VLBI interferometer with a ground-space arm will operate. The interferometer will have extraordinary angular resolution of a few microarcsecond (μas) at the shortest wavelength (1.35 cm). Since typical angular scales for gravitational microlensing are at the μas level for cosmological locations of sources and microlenses, in principle there is a chance to resolve microimages and (or) at least, detect astrometrical shift of bright point like images. In particular, gravitationally lensed systems, such as B1600+434, where in radio band a signature of microlensing is found, look suitable for direct observations of microlensing, since microlensing with the RadioAstron interferometer may be detected in the future (considering its high angular resolution and a relatively high sensitivity and assuming a ground support by the advanced radio telescopes).

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Winchen, T., A. Bonardi, S. Buitink, A. Corstanje, H. Falcke, B. M. Hare, A. Hörandel et al. "Properties of the Lunar Detection Mode for ZeV-Scale Particles with LOFAR". EPJ Web of Conferences 216 (2019): 04010. http://dx.doi.org/10.1051/epjconf/201921604010.

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The steep decrease of the flux of ultra-high energy cosmic rays (UHECR) provides a challenge to answer the long standing question about their origin and nature. A significant increase in detector volume may be achieved byemploying Earth’s moon as a detector that is read out using existing Earth-bound radio telescopes by searching for the radio pulses emitted by the particle shower in the lunar rock. In this contribution we will report on the properties of a corresponding detection mode currently under development for the LOFAR Radio telescope.

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49

Wright, Melvyn. "Adaptive Real-Time Imaging Synthesis Telescopes". International Journal of High Performance Computing Applications 26, n.º 4 (8 de junho de 2012): 358–66. http://dx.doi.org/10.1177/1094342012445626.

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The digital revolution is transforming astronomy from a data-starved to a data-submerged science. Instruments such as the Atacama Large Millimeter Array (ALMA), the Large Synoptic Survey Telescope (LSST), and the Square Kilometre Array (SKA) will measure their accumulated data in petabytes. The capacity to produce enormous volumes of data must be matched with the computing power to process that data and produce meaningful results. In addition to handling huge data rates, we need adaptive calibration and beamforming to handle atmospheric fluctuations and radio frequency interference, and to provide a user environment which makes the full power of large telescope arrays accessible to both expert and non-expert users. Delayed calibration and analysis limit the science which can be done. To make the best use of both telescope and human resources we must reduce the burden of data reduction. We propose to build a heterogeneous computing platform for real-time processing of radio telescope array data. Our instrumentation comprises a flexible correlator, beam former, and imager that is based on state-of-the-art digital signal processing closely coupled with a computing cluster. This instrumentation will be highly accessible to scientists, engineers, and students for research and development of real-time processing algorithms, and will tap into the pool of talented and innovative students and visiting scientists from engineering, computing, and astronomy backgrounds. The instrument can be deployed on several telescopes to get feedback from dealing with real sky data on working telescopes. Adaptive real-time imaging will transform radio astronomy by providing real-time feedback to observers. Calibration of the data is made in close to real time using a model of the sky brightness distribution. The derived calibration parameters are fed back into the imagers and beam formers. The regions imaged are used to update and improve the a priori model, which becomes the final calibrated image by the time the observations are complete.

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Kol'tso, N. E., S. A. Grenkov e L. V. Fedotov. "Comparison of Radio Interferometers with Analog and Digital Extraction of Recorded Signal". Journal of the Russian Universities. Radioelectronics 23, n.º 2 (28 de abril de 2020): 6–18. http://dx.doi.org/10.32603/1993-8985-2020-23-2-6-18.

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Introduction. Radio telescopes of Very Long Baseline Interferometry (VLBI) networks usually record several signals with relatively narrow (up to 32 MHz) bands, which are extracted by means of base band converters (BBC) from an analog noise signal of an intermediate frequency (IF) with bands up to 1 GHz. When processing data, frequency band synthesis is used. At new small radio telescopes (for example, RT-13), directly wideband IF signals are digitized. An ability to connect the RT-13 radio telescope to the “Quasar” VLBI complex and to international VLBI networks provides by a digital narrow-band signal extraction module developed in 2019.Aim. Determining the measuring accuracy of an interferometric group delay of a signal by a radio interferometer with a digital narrow-band signal extraction module and comparing the sensitivity of interferometers with analog and digital signal extraction systems.Materials and methods. Sensitivity losses of interferometers with different systems for detecting recorded signals were calculated. The accuracy of a multi-channel interferometer with the synthesis of a frequency band and of an interferometer with recording of digital broadband IF signals without band synthesis was compared. The results were confirmed by VLBI observations in the observatories of the “Quasar” complex.Results. When replacing the analog system of signal extraction with digital system the sensitivity losses of the interferometer were slightly reduced. The measurement accuracy of the interferometric group delay had not changed. Accuracy increased when digitally recording broadband IF signals and when synthesizing a frequency band significantly larger than the IF bandwidth. Conditions and minimum synthesized bands were determined under which the accuracy of the interferometer with the registration of narrowband signals can be higher than the accuracy of the interferometer with the registration of wideband IF signals.Conclusion. The problem of combining RT-13 radio telescopes with VLBI networks with recording of video frequency signals was solved. The efficiency of the installation of digital signal conversion systems at radio telescopes was shown.

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