Small Radio Telescope Research Articles

Improving Radio Signal from Baghdad University Radio Telescope Using the Savitzky-Golay Filter

Astronomical radio observations from a small radio telescope suffer from various types of noise. Hence, astronomers continuously search for new techniques to eliminate or reduce such noise and obtain more accurate results. This research investigates the impact of implementing the Savitzky-Golay filter on enhancing radio observation signals retrieved from the Baghdad University Radio Telescope (BURT). Observations from BURT were carried out for different Galactic coordinates, and then a MATLAB code was written and used to implement the Savitzky-Golay filter for the collected data. This process provides an assessment of the ability of the filter to reduce noise and improve the quality of the signal. The results of this research clearly showed that applying the Savitzky-Golay filter reduces the noise and enhances the signal of astronomical radio observations. However, the filter should be used appropriately to preserve the original features of the signal. In conclusion, the filter is considered an efficient tool for enhancing the radio signal by reducing the noise and smoothing the signal. Therefore, the filter provides a substantial contribution and improvement to the field of radio astronomy.

Control system performance of a 7.3-meter radio telescope converted from telecommunication antenna to radio astronomy purposes in Malaysia

We present a crucial step in converting a commercial telecommunication antenna system into a radio astronomy telescope. This step involved the development of a newly installed and simple control system to manage the telescope movement with relatively good pointing accuracy. The control system was designed using a programmable logic controller (PLC) that is robust and affordable. Based on the performance testing, this control system achieved average accuracies of 0.95 and 1.083 arcmin in azimuth and elevation positioning respectively, and an RMS of 9 arcmin across the open sky. In addition, it reached average rotation speeds of about 5.4, 2.4, and 4.8 arcmin/s for azimuth, elevation, and tracking rate, respectively. The results also showed that the converted radio telescope has an acceptable tracking accuracy of errors below 10% of the antenna half-power bandwidth at a frequency of 1.4 GHz while generating movement speed suitable for basic radio astronomy observations. These results show that this converted small radio telescope has the basic requirements for tracking and imaging celestial radio objects, primarily via interferometry with larger radio telescopes at low observation frequencies.

Simulation of Small Radio Telescope Antenna Parameters at Frequency of 1.42 GHz

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.

The pointing model of 4.5-m small radio telescope at NARIT

The efficiency of a radio telescope decisively depends on its pointing accuracy. Telescope’s pointing model (PM) contains repeatable errors due to the antenna control system’s imperfections, which can be corrected during observation. The 4.5m Small Radio Telescope (SRT’s) has been developed for education and experiments at Astropark, National Astronomical Research Institute of Thailand (NARIT), Chiang Mai (18°N 51’ 5” and 98°E 57’ 27”). We have implemented a 10-cm optical camera system installed on the SRT’s antenna structure to measure the offset of individual pointing covering all sky direction, which then are modeled, and the telescope’s PM is obtained. Here, we report preliminary results of SRT’s PM, where we obtain for each epoch -551.116 and -3811.549 arcsec for Azimuth encoder offset, and 1217.105 and -3343.866 arcsec for Elevation encoder offset. More accurate results can be obtained with better sky coverage observation.

A sky survey of neutral Hydrogen at 21 cm using NARIT 4.5m small radio telescope

We surveyed the neutral hydrogen (HI) at 21 cm by using the 4.5m Thai Small Radio Telescope (SRT) of the National Research Institute of Thailand (NARIT) during January–March 2019. The main aim of this project is for doing the distribution maps of HI in our Galaxy which will be shown in terms of the radial velocities and the HI positions in the galactic coordinate. The selected positions are mainly along the galactic plane (above or under the plane) within 21 degrees. The galactic longitudes are during 0 to 258 degrees. According to studies, the spectrum mode of NARIT-SRT receiver is recorded and divided into 400 channels with the velocity resolution ∼1.05 kms-1. Full width at half maximum (FWHM) of the NARIT - SRT is about 3-4 degrees. Its system temperature is 147.5 ± 5.1 K. The distribution map of HI clouds at 21 cm with the NARIT-SRT is presented in term of the radial velocity (vr) in the range of [0: +220] kms-1 and the column density of HI down to the level 1019 per cm-2. Our results are in good agreement with theoretical values and international database.

The mass distribution and the rotation curve of the Milky Way Galaxy using NARIT 4.5 m small radio telescope and the 2.3 m Onsala radio telescope

This study was aimed to make the neutral hydrogen (HI) mapping and rotation curve of the Milky Way at galactic longitude 0° to 90° in the galactic plane by using the 4.5 m Small Radio Telescope (SRT) of National Astronomical Research Institute of Thailand (NARIT) and the 2.3 m Onsala radio telescope. The HI spectra at wavelength of 21 cm can be used to analyze the dynamical properties of the Milky Way with Gaussian fitting software, which was developed by using Python programming language. SalsaJ is another free astronomical software which was also used in this study by analyzing the Gaussian spectra of the Onsala radio telescope. For making sure the performance of developed software, therefore, it will be tested between their observation spectra of NARIT 4.5 m SRT and the Onsala radio telescope together with the public international archive. The results showed that the positions of HI are distributed in a spiral - arms shape and the rotation curve is constant at the galactic distance (R) > 3 kpc. The spherical mass distribution (in terms of the surface mass density) was approximated by directly using rotation curve. Our results are in good agreement with the standard values.

Demonstrating the Principles of Aperture Synthesis with Table- Top Laboratory Exercises

Many undergraduate radio astronomy courses are unable to give a detailed treatment of aperture synthesis due to time constraints and limited math backgrounds of students. We have taken a laboratory-based approach to teaching radio interferometry using a set of college-level, table-top exercises. These are performed with the Very Small Radio Telescope (VSRT), an interferometer developed at the Haystack Observatory using satellite TV electronics as detectors and compact fluorescent light bulbs as microwave signal sources. The hands-on experience provided by the VSRT in these labs allows students to gain a conceptual understanding of radio interferometry and aperture synthesis without the rigorous mathematical background traditionally required. The data are quickly and easily processed using a user-friendly data analysis Java package, VSRTI_Plotter.jar. This software can also be used in the absence of the equipment as an interactive computer activity to demonstrate an interferometer’s responses to assorted surface brightness distributions. The students also gain some familiarity with Fourier transforms and an appreciation for the Fourier relations in interferometry using another Java package, the Tool for Interactive Fourier Transforms (TIFT). We have successfully used these tools in multiple offerings of our radio astronomy course at Union College

The VATLY Radio Telescope

A small radio telescope (SRT) has been installed on the roof of the Hanoi astrophysics laboratory VATLY. It is equipped with a 2.6 m diameter mobile parabolic dish remotely controlled in elevation and azimuth and with super-heterodyne detection around the 21 cm hydrogen line. First results of observations of the Sun and of the centre of the Milky Way are presented. They demonstrate the high quality of the telescope performance and are used to evaluate lobe size, signal to noise ratios, anthropogenic interferences and measurement accuracies. Particular attention is given to the measurement of the pointing accuracy. The rich measurement programme that is now at hand is briefly sketched.

Revealing the Hidden Wave: Using the Very Small Radio Telescope to Teach High School Physics

Scientists and teachers have worked together to produce teaching materials for the Very Small Radio Telescope (VSRT), an easy-to-use, low-cost apparatus that can be used in multiple laboratory experiments in high school and university physics and astronomy classes. In this article, we describe the motivation for the VSRT and several of the laboratory investigations that are being used in local high schools.

Interactive Lab to Learn Radio Astronomy, Microwave & Antenna Engineering at the Technical University of Cartagena (Spain)

An initiative carried out at the Technical University of Cartagena (UPCT, Spain) to encourage students and promote the interest for Scientific and Engineering Culture between society is presented in this contribution. For this purpose, a long-term project based on the set-up of an interactive laboratory surrounding a small Radio Telescope (SRT) system has been carried out. The main novelty is that this project is entirely being developed by students of last courses of our Telecommunication Engineering Faculty, under the supervision of four lecturers. This lab offers the possibility to remotely control the SRT, and it provides a set of multimedia web-based applications to produce a novel, practical, multidisciplinary virtual laboratory to improve the learning and teaching processes in related sciences and technologies.

A Simple Radio Telescope Operating at Ku Band for Educational Purposes

A small radio telescope has been developed, which can be installed at high schools and universities to further the interest of students in science and technology. The telescope kit is based on existing commercially available satellite television equipment. Safe assembly and operation of the telescope were primary drivers in the design of the system, along with the need to keep the cost down to ~6,000 Euros. The telescope uses a 1.2 m diameter dish and a receiver operating at Ku band (10-12 GHz). The system has a basic tracking capability, and is remotely commanded through a computer interface. Detailed user-friendly manuals were written to enable students to assemble, calibrate, and operate the telescope themselves, under the guidance of a high school teacher. The performance of the prototype telescope was evaluated, and sun and moon observations were executed. Although the low cost of the system leads to limitations in sensitivity and pointing accuracy, there are nonetheless significant pedagogical benefits from this project in a variety of educational subjects involving science and technology. A number of extensions to the basic telescope kit may be implemented to improve its performance

Astronomy and particle physics research classes for secondary school students

During a 10-day course in astronomy and particle physics, two research classes with 17–18 year old secondary school students studied the differential rotation of the milky way, the intricacies of high energy particle collisions and learned about the origin of the universe. The combination of making their own measurements of the milky way with a small radio telescope, using scientific data from high energy particle collisions, and having the big bang explained by scientists created an attractive and fascinating course in contemporary science.

Closed cycle refrigerator for superconducting mm wave-mixers

We describe the construction and operation of a closed cycle refrigerator with an operating temperature of 2.8 K. Helium gas at a pressure of 1.2 MPa is precooled to 18 K by a Stirling refrigerator (CTI 350) and expanded in a Joule-Thomson stage to ≈10 kPa. A vacuum pump circuit and compressor bring the gas back to its original pressure. The refrigerator is designed to cool the first stages of a radio astronomical receiver with a superconducting (SIS) mixer. It fits into a small radio telescope and works widely independent of orientation. After a cooldown time of 12–14 h a cooling capacity of 200–250 mW is available.

Radioastronomical measurements of ionospheric electron content

Observations are presented of the variation with local time of the position angle of celestial polarisation at the North Pole. The observations show that: 1. (a) For radioastronomical studies, if frequent polarisation measurements at the pole are incorporated into an observing schedule, then the ionospheric rotation of position angle, and thus the extraionospheric position angles of polarisation of celestial sources, may be conveniently determined. 2. (b) For ionospheric studies, a continuous and accurate monitor of the columnar electron content may be derived, referred to a fixed subionospheric point. This suggests that a small radio telescope could be set up to permanently observe the polarisation of the pole, so providing an unbroken series of n t measurements. 3. (c) On many nights there is a secondary maximum in n t around 02h local time. This is probably due to a downward flux of electrons from the protonosphere, related to the heating by conjugate photoelectrons.

Solar Temperature at 2-mm Wave-length

ONE of the items developed for microwave diagnostic purposes on Zeta is a harmonic-mixing superheterodyne radiometer, working at a wave-length of about 2 mm. This radiometer has been used together with a small radiotelescope for measuring the apparent temperature of the Sun at a wave-length of 2.04 mm.