Search

Fast radio bursts (FRBs) are extraordinary astrophysical phenomena characterized by short radio pulses that last only a few milliseconds, yet their power can surpass that of 500 million suns. To date, most detected FRBs originate from beyond our galaxy. However, if an FRB were to originate within the Milky Way, it could be detected using small antennas. In this paper, we propose a compact and ad-hoc antenna array designed for the efficient detection and localization of FRBs within the Milky Way. The antenna operates within the 1200–1800MHz range and consists of three sub-arrays placed in an L-shape for source localization, occupying a total volume of 80×25×6cm3. Each sub-array consists of 4 miniaturized, dual-polarized, half-space radiation antenna elements, forming a one-dimensional array that allows shaping the radiation pattern to match the form of the Milky Way without exhibiting grating lobes. A prototype was constructed and characterized to validate the design. The measured results exhibit good agreement with the simulations. In addition to having a custom elongated radiation pattern, the array has attractive merits, such as low reflections at the input ports, high radiation efficiency, and a distribution that inhibits the existence of phase ambiguities, thus facilitating source localization. [ABSTRACT FROM AUTHOR]

The next generation phased array radio telescopes, such as the Square Kilometre Array (SKA) low frequency aperture array, suffer from RF interference (RFI) because of the large field of view of antenna element. The classical station beamformer used in SKA-low is resource efficient but cannot deal with the unknown sidelobe RFI. A real-time adaptive beamforming strategy is proposed for SKA-low station, which trades the capability of adaptive RFI nulling at an acceptably cost, it doesn't require hardware redesign but only modifies the firmware accordingly. The proposed strategy uses a Parallel Least Mean Square (PLMS) algorithm, which has a computational complexity of 4 N + 2 and can be performed in parallel. Beam pattern and output SINR simulation results show deeply nulling performance to sidelobe RFI, as well as good mainlobe response similar to the classical beamformer. The convergence performance depends on the signal-and-interference environments and step size, wherein too large a step size leads to a non-optimal output SINR and too small a step size leads to slow convergence speed. FPGA implementation demonstrations are implemented and tested on a NI FPGA module, and test results demonstrate good real-time performance and low slice resource consumption. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ephemeral Fast Radio Bursts (FRBs) must be powered by some of the most energetic processes in the Universe. That makes them highly interesting in their own right, and as precise probes for estimating cosmological parameters. This field thus poses a unique challenge: FRBs must be detected promptly and immediately localised and studied based only on that single millisecond-duration flash. The problem is that the burst occurrence is highly unpredictable and that their distance strongly suppresses their brightness. Since the discovery of FRBs in single-dish archival data in 2007, detection software has evolved tremendously. Pipelines now detect bursts in real time within a matter of seconds, operate on interferometers, buffer high-time and frequency resolution data, and issue real-time alerts to other observatories for rapid multi-wavelength follow-up. In this paper, we review the components that comprise a FRB search software pipeline, we discuss the proven techniques that were adopted from pulsar searches, we highlight newer, more efficient techniques for detecting FRBs, and we conclude by discussing the proposed novel future methodologies that may power the search for FRBs in the era of big data astronomy. [ABSTRACT FROM AUTHOR]

تداخل الترددات الراديوية يمثل الضعف في استلام الإشارة الراديوية الفضائية و تكون هذه التداخلات ناتجة عن صنع الانسان حيث تعمل على تقليل جوده استلام الإشارة الفضائية والتي تتأثر بالغلاف الجوي الاتموسفير والنشاط الشمسي وكل النشاطات القريبة من التلسكوب. في هذه الدراسة تم رصد ظاهرة الكسوف الجزئي في العاصمة بغداد باستخدام الجهاز HSA2000 series receiver spectrum analyzer والمربوط مع هوائيين ثنائي القطب ضمن الترددات المنخفضة ( ١٥ - ٨٠) والتردد العالي ( ۱۱۰ - ٢٤٠) والتي صممت في مختبر الفلك الراديوي للدراسات العليا في قسم الفلك والفضاء بجامعة بغداد حيث تم مقارنة هذه القراءات مع الأيام الاعتيادية حيث وجد ان نسبة الضوضاء في يوم الكسوف الى يوم اعتيادي في نفس وقت الرصد يساوي (۰٫۹۳) للتردد المنخفض و (٠,٨٥) للتردد العالي، وكذلك وجد تقارب كبير بين معدل الاشارة المرصودة خلال الكسوف الجزئي و معدل القيم المرصودة خلال فترة الليل والتي تفسر بسبب نقصان الكثافة الالكترونية لايونوسفير وكذلك الضوضاء الناتجة من النشاط البشري في منطقة الرصد . حيث كالنت النسبة (۰,۹۸) و (۰,۹۷) للترددات المنخفضة والعالية على التوالي. حيث يعمل الكسوف على تقليل الضوضاء بالرغم من الفترة القصيرة لكسوف الشمس ووجد علاقة وثيقة بين ذروة الكسوف الجزئي مع قوة الإشارة المستلمة [ABSTRACT FROM AUTHOR]

The Atacama Large Millimeter/submillimeter Array (ALMA) represents a significant advancement in contemporary astronomy, operating within a frequency range spanning from 35 to 950 GHz, encompassing millimeter and submillimeter wavelengths. This broad spectrum allows ALMA to delve into the depths of the cosmos, unveiling celestial phenomena with unparalleled precision and complexity. To allow the receivers of the ten frequency bands to view the sky alternatively, the telescope adopts an off-axis feed system. At the heart of this system are focusing components, which are typically paired mirrors positioned along the optical path from the feed horn to the Cassegrain secondary focus. These mirrors play a critical role in directing the beam emitted by the off-axis feed horn to accurately illuminate the hyperboloid secondary reflector of the Cassegrain antenna. The precise configuration of these mirrors plays a critical role since the slightest deviation from their optimum parameters may give rise to an unacceptable increase in cross-polarization and distortion effects. In this paper, we present a complete scheme outlining the complex procedure of defining the shapes, dimensions, alignments, and positions of these mirrors, providing a comprehensive framework for the development of ALMA's receiver optics. We thoroughly explain key equations necessary for optimal functionality, imparting valuable insights into the technical complexities behind ALMA's cutting-edge capabilities. The ALMA Band 7 receiver optics has been used to elucidate the design methodology. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The next generation phased array radio telescopes, such as the Square Kilometre Array (SKA) low frequency aperture array, suffer from RF interference (RFI) because of the large field of view of antenna element. The classical station beamformer used in SKA-low is resource efficient but cannot deal with the unknown sidelobe RFI. A real-time adaptive beamforming strategy is proposed for SKA-low station, which trades the capability of adaptive RFI nulling at an acceptably cost, it doesn’t require hardware redesign but only modifies the firmware accordingly. The proposed strategy uses a Parallel Least Mean Square (PLMS) algorithm, which has a computational complexity of 4N+2 and can be performed in parallel. Beam pattern and output SINR simulation results show deeply nulling performance to sidelobe RFI, as well as good mainlobe response similar to the classical beamformer. The convergence performance depends on the signal-and-interference environments and step size, wherein too large a step size leads to a non-optimal output SINR and too small a step size leads to slow convergence speed. FPGA implementation demonstrations are implemented and tested on a NI FPGA module, and test results demonstrate good real-time performance and low slice resource consumption.

A partial solar eclipse occurred on 25 October 2022, in the central and northern parts of Europe. The partial solar eclipse was observed at Aalto University Metsähovi Radio Observatory, Finland at the radio wavelength of 8 mm (37 GHz). In Finland, the magnitude of the partial solar eclipse was 62.7 %. Solar radio maps at the time cadence of about 9 minutes were observed over the whole eclipse. The solar eclipse observations could be used for instrument calibration purposes. This paper investigates the solar brightness temperature, the limb brightening effect, the height of the chromosphere and the location of radio brightening using the aforementioned partial solar eclipse observations. We got the confirmation that our earlier results are consistent, e.g., the solar brightness temperature matches with 8100 K ± 300 K. It was also possible to detect limb brightening effect. However, the prevailing solar activity might have distorted the final conclusions. The Moon should operate as a focusing element and the location of radio brightenings could be defined more carefully than in the normal conditions. We investigated this feature. Our results are in some parts unexpected and need further investigations. [ABSTRACT FROM AUTHOR]

Low-frequency aperture arrays represent sensitive instruments to detect signals from radio astronomic sources situated in the universe. In Italy, the Sardinia Aperture Array Demonstrator (SAAD) consists of an ongoing project of the Italian National Institute for Astrophysics (INAF) aimed to install an aperture array constituted of 128 dual-polarized Vivaldi antennas at the Sardinia Radio Telescope (SRT) site. The originally envisaged 128 elements of SAAD were re-scoped to the 16 elements of its precursor named SADino, with the aim to quickly test the system with a digital beam-former based on the Italian Tile Processing Module (iTPM) digital back-end. A preliminary measurements campaign of radio frequency interference (RFI) was performed to survey the less contaminated spectral region. The results of these measurements permitted the establishment of the technical requirements for receiving a chain for the SADino telescope. In this paper, the design, implementation, and characterization of this signal acquisition chain are proposed. The operative frequency window of SAAD and its precursor, SADino, sweeps from 260 MHz to 420 MHz, which appears very attractive for radio astronomy applications and radar observation in space and surveillance awareness (SSA) activities. [ABSTRACT FROM AUTHOR]

The dynamic response of a radio telescope structure under wind load excitation significantly impacts the accuracy of signal reception. To address this issue, this study established a parametric finite element model of a radio telescope to simulate its dynamic response under wind load excitation. An improved Latin hypercube sampling method was applied in the design of experiments (DOEs) to optimize the structural dimensional parameters of various components of the radio telescope with the aim of reducing the dynamic response to wind load. A response surface model and multi-objective genetic algorithm (MOGA) were employed for multi-objective structural optimization of the radio telescope structure. The findings reveal that the thickness of the stiffening ribs, the length of the side of the square hollow pole, the thickness of the middle pole, and the inner diameter of the thin pole are the most influential structural parameters affecting the first-order frequency (F1), second-order frequency (F2), maximum deformation in the x-direction (DX), and maximum deformation in the z-direction (DZ) of the radio telescope, respectively. Optimizing the radio telescope results in a 40.00% improvement in F1 and a 24.16% enhancement in F2, while reducing DX by 43.94% and DZ by 64.25%. The study outcomes offer a comprehensive scheme for optimizing the structural dimensional parameters of various radio telescope components in regions characterized by multiple wind fields. [ABSTRACT FROM AUTHOR]

Measurements of the flux densities of the supernova remnant (SNR) G74.9+1.2 (CTB 87) at frequencies of 4840 and 8450 MHz were carried out with the RT-32 radio telescope of the Svetloye observatory of the Institute of Applied Astronomy, Russian Academy of Sciences (IAA RAS), in 2018–2019. The data contain signs of the presence of a source of a variable component in the radio emission on a time scale of a month or more. The flux densities of G74.9+1.2 over the time interval 1959.7–2010 are determined from published data, which allow the intensity of G74.9+1.2 to be compared with standard sources. All the data are presented in a single system based on the exact scale of "artificial moon" (AM) fluxes. A refined spectrum of SNR G74.9+1.2 was obtained. The totality of available data is approximated by two power-law sections with different spectral indices: at frequencies and at . The projections of two power-law sections intersect at a frequency MHz. The break in the radio spectrum of the source, considering its age (more than 4000 years), could form as a result of synchrotron losses. The increase in the steepness of the spectrum close to 0.5 above the frequency is an argument in favor of such an assumption. The totality of data obtained during measurements on the RT-32 and on the basis of published works allows us to state that the variable component in the G74.9+1.2 radio emission on all time scales is much less pronounced compared to younger PWNs. As a possible mechanism for the observed variability, a reconnection of the magnetic field lines in the pulsar magnetosphere is proposed. [ABSTRACT FROM AUTHOR]

Radiofrequency interference (RFI) describes the weakening of radio astronomy transmissions caused by man-made radio signal noise in radio telescope observation indicates the level of radio frequency noise in the sky at all times, regardless of any astronomical sources. This noise is affected by various sources, including Earth's atmosphere or solar activity and all communications equipment operating near the radio telescope. In this study, the background noise which includes RFI was measured using HSA2000 series receiver spectrum analyzer, which connected with two dipole antennas in different frequency bands (15-80 MHz) low band antenna, and (110-240 MHz) high band antenna during the partial solar eclipse in Baghdad on October 25, 2022, at (12:00-15:00), as a simple radio telescope to observe the radio astronomical background level in the sky. It is clear that the average amount of RFI level during a partial solar eclipse (-83.249 dBm for LBA decreased by about (0.93) from the value on a normal day (-77.495 dBm). And For HBA -84.711 dBm decreased by about (0.85) from the value on a normal day (-72.784 dBm). Also, it was noticed that these amounts are approximately equal to the RFI level at night (-82.352 dBm for LBA and -82.739 dBm for HBA). It is (0.98) for LBA and (0.97) for HBA, respectively. This research confirms that despite the short duration of the partial eclipse, the average value during the partial eclipse period is close to the average values during the night period due to the decrease in the electronic density of the ionosphere, especially at low frequencies, and the FRI of ground disturbances as a result of the activities of human from the surrounding the monitoring area. also, found that at the monitoring point, there is a good relationship between the time of the maximum partial eclipse and the peaks of signal gain strength.

Subject and Purpose. Since decameter carbon radio recombination lines (RRLs) were detected for the first time more than forty years ago, they have significantly extended our knowledge of the physics, kinematics and chemistry of the cold rarefied interstellar medium (ISM). A large number of these lines have been observed towards various Galactic radio sources. The present paper describes our studies of decameter carbon RRLs in such Galactic directions as the sight-lines to the S140 emission nebula and to the large volume of cold neutral hydrogen known as the GSH 139-03-69 super shell. Methods and Methodology. Observations within a 1-MHz frequency band centered at 26 MHz were performed using the UTR-2 radio telescope and a multi-channel digital correlator. The UTR-2 is still the world largest and the most sensitive low-frequency radio telescope. Results. We report the detection of decameter carbon RRL series C627α – C637α from the medium lying towards the S140 nebula. The extents of RRL forming regions have been estimated. It is suggested that RRLs in the S140 direction are formed in the local ISM lying along the line of sight. The RRL-forming region is probably associated with omnipresent diffuse neutral HI gas in the Galactic plane rather than with S140 nebula itself. Toward the GSH 139-03-69 super shell, decameter RRLs have been detected as well. Likewise, they apparently originate from the local medium lying along the sight-line. Yet, the spectrum contains a RRL component corresponding to the absorption of the cold gas of the GSH 139-03-69 itself in the ISM. Conclusions. The obtained results indicate great possibilities of decameter carbon RRLs not only for cold ISM probing but also for making a good auxiliary tool for studying large complexes of extremely cold hydrogen HI in the Galaxy.

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.

Radio frequency interference (RFI) represents all unwanted signals detected by radio receivers of a telescope. Unfortunately, the presence of RFI is significantly increasing with the technological development of wireless systems around the world. For this reason, RFI measurement campaigns are periodically necessary to map the RFI scenario around a telescope. The Sardinia Radio Telescope (SRT) is an Italian instrument that was designed to operate in a wide frequency band between 300 MHz and 116 GHz. One of the receivers of the telescope is a coaxial cryogenic receiver that covered a portion of the P and L bands (i.e., 305–410 MHz and 1300–1800 MHz) in its original version. Although the receiver was used for years to observe bright sources with sufficient results, its sub-bands can be redesigned considering the most recently evolved RFI scenario. In this paper, the results of a RFI measurement campaign are reported and discussed. On the basis of these results, the new sub-bands of the L-P receiver, together with the design of the new microwave filter selector block of the SRT receiver, are presented. In this way, SRT will cover up to 120 MHz and 460 MHz of −3 dB bandwidth at the P-band (290–410 MHz) and L-band (1320–1780 MHz), respectively. The bands of these filters are selected to reject the main RFI with high levels of amplitude and optimize the estimated antenna temperature and sensitivity of the receiver during the research activities, such as pulsar observations, very long baseline interferometer applications and spectroscopy science. [ABSTRACT FROM AUTHOR]

Two infrared thermal imagers have been installed on the TianMa radio telescope (TMRT) to continuously monitor the temperature distributions of the back-up structure (BUS). In order to compensate the measurement error of the infrared thermal imager (ITI) for a BUS, a correction formula, as a function of measuring distance and viewing angle, is proposed. According to the relationship between the locations of the measurement points in the thermographic image and those in the actual structure, the 3D coordinates of the measurement points are determined by a finite element model of the BUS. Then, the measuring distances and viewing angles are calculated using 3D coordinates of the measurement points. The measurement accuracy of the ITI improves from ±2 ∘ C to ±0.5 ∘ C with the proposed formula. Additionally, based on the information of rotation angle and rotation speed of the elevation, the problem of the ITI moving with the elevation of the telescope in real time is solved. The temperature data at each elevation are recorded in excel documents respectively which are integrated into a document in chronological order through compiling program. Finally, the temperature of the measurement points at different altazimuthal positions is displayed as curves or contours. The thermal states of about 40% measuring points of the BUS are simultaneously monitored by the ITI, which provides accurate temperature distribution for the prediction of thermal deformations of the BUS. [ABSTRACT FROM AUTHOR]

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 gravity can be corrected. The structural design aims to ultimately allow high-sensitivity observations from 150 MHz up to 115 GHz. To satisfy the requirements for early scientific goals, the QTT will be equipped with ultra-wideband receivers and large field-of-view multi-beam receivers. A multi-function signal-processing system based on RFSoC and GPU processor chips will be developed. These will enable the QTT to operate in pulsar, spectral line, continuum and Very Long Baseline Interferometer (VLBI) observing modes. Electromagnetic compatibility (EMC) and radio frequency interference (RFI) control techniques are adopted throughout the system design. The QTT will form a world-class observational platform for the detection of low-frequency (nanoHertz) gravitational waves through pulsar timing array (PTA) techniques, pulsar surveys, the discovery of binary black-hole systems, and exploring dark matter and the origin of life in the universe. The QTT will also play an important role in improving the Chinese and international VLBI networks, allowing high-sensitivity and high-resolution observations of the nuclei of distant galaxies and gravitational lensing systems. Deep astrometric observations will also contribute to improving the accuracy of the celestial reference frame. Potentially, the QTT will be able to support future space activities such as planetary exploration in the solar system and to contribute to the search for extraterrestrial intelligence. [ABSTRACT FROM AUTHOR]

The low‐latitude ionosphere is a dynamic region with a wide range of disturbances in temporal and spatial scales. The Giant Metrewave Radio Telescope (GMRT) situated in the low‐latitude region has demonstrated its ability to detect various ionospheric phenomena. It can detect total electron content (TEC) variation with precision of 10−3 TECU and also can measure TEC gradient with an accuracy of about 7 × 10−4 TECU km−1. This paper describes the spectral analysis of previously calculated TEC gradient measurements and validates them by comparing their properties using two bands. The analysis tracked individual waves associated with medium‐scale traveling ionospheric disturbances (MSTIDs) and smaller waves down to wavelengths of ∼10 km. The ionosphere is found to have unanticipated changes during sunrise hours, with waves changed propagation direction as the sun approached the zenith. Equatorial spread F disturbances during sunrise hours is observed, along with smaller structures moving in the same direction. Plain Language Summary: The Earth's ionosphere can limit exploring sub‐GHz frequencies of the sky and introduces an extra phase term that is difficult to calibrate. The same calibration data can be used to study the Earth's ionosphere more precisely than conventional probes. Radio interferometry is a technique for studying astronomical sources and Earth's ionosphere by measuring the spatial coherence function of multiple elements. The GMRT is a unique instrument for exploring the equatorial ionosphere region. This study used dual‐band observations of a bright radio source with the GMRT to explore the Equatorial Ionization Anomaly region. The GMRT can detect variations in total electron content and measure TEC gradient with high accuracy. Spectral analysis was performed on TEC gradient measurements to track individual waves associated with medium scales traveling ionospheric disturbances and smaller waves up to wavelengths of about ∼10 km. The results showed unexpected changes in the ionosphere during sunrise hours and observed large plasma irregularities and smaller structures moving in the same direction. Key Points: Giant Metrewave Radio Telescope (GMRT) can demonstrate an order of magnitude better sensitivity than GNSS‐based TEC measurements in characterizing ionospheric fluctuationsThe spectral analysis technique used with GMRT can detect multiple MSTIDs and smaller‐scale structures simultaneouslyGMRT can detect ionospheric variations as small as 10 km. The study also showed waves changing direction unexpectedly during sunrise time [ABSTRACT FROM AUTHOR]

It has been shown that bistatic radars using radio telescopes as receivers can be used to increase the sensitivity of orbital debris measurements over traditional terrestrial monostatic radar. A method to calculate the lateral surface area of a bistatic radar is needed to evaluate the efficacy of a proposed bistatic radar configuration for orbital debris measurements. For over three decades, models of the orbital debris (OD) environment in low Earth orbit (LEO) have been developed to assess the risk posed by OD to spacecraft. While terrestrial radar measures debris 3 mm and larger and in situ measurements provide data for debris smaller than 1 mm, no good data sources exist for debris between 1 mm and 3 mm in size. This results in large variations between competing OD models. It also happens to be the size regime which poses the highest mission-ending risk to spacecraft. It is, therefore, of interest to investigate potential new data sources for this under-sampled size regime. There are many radars and radio telescopes that could be combined to create sensitive bistatic radars that could potentially bridge the size gap. In addition to sensitivity, it is necessary to predict the expected count rate of a candidate sensor to evaluate its performance. NASA's Orbital Debris Engineering Model (ORDEM) can be used to predict the flux of debris passing through the line of sight of a radar or telescope. This flux is related to a count rate through the calculation of the lateral surface area of the sensor. While this can be done easily for monostatic radars, a method for calculating the lateral surface area of a bistatic radar is needed. This new method of calculation has been developed and is described. The new method maps the radar beam overlap in 3D space, calculating the area of the complex surface formed by the gain product of the two antennas. Comparisons of the monostatic and new bistatic lateral surface area calculation methods for the monostatic case are presented. Results of a sample lateral surface area calculation for a bistatic radar observation configuration currently employed by NASA are shown. Finally, a guide for total error as a function of baseline and target altitude is established. [ABSTRACT FROM AUTHOR]

One of the key reasons for the deterioration of antenna pointing accuracy for radio telescopes is the deformation and tilt of antenna alidades, which primarily result from track unevenness and thermal gradients. A high-precision inclinometer measurement system is installed to investigate the tilt of the antenna alidade and the pointing errors caused thermally. An environment control box with a leveling base was designed to reduce the interference of the external environment, which proved to be effective in guaranteeing the zero-point stability and repeat accuracy of the inclinometer. The tilt of the alidade caused by the track unevenness was measured by a test of slowly rotating the antenna along the azimuth at windless nighttime. A 5-day antenna stationary test and a 48 h astronomical pointing error measurement were performed, which proved the inclinometer measurement system is capable of measuring the thermally induced inclinations with acceptable accuracy. Through a preliminary compensation experiment, the pointing error is compensated from 37″ to 12″, which shows that the application of the system has a good effect on improving the pointing accuracy of the antenna. The system with high measurement accuracy, good system stability, and low computational complexity, proves an effective tool for the radio telescope to solve the problem of real-time measurement and compensation for antenna pointing errors. [ABSTRACT FROM AUTHOR]

This work is concerned with a detailed study of an active antenna, which can serve as a prototype of a phased array antenna element for a future lunar very-low-frequency (VLF) radio telescope operating in the frequency range of 1–30 MHz. The antenna consisted of a ribbon symmetrical dipole and a low-noise preamplifier. A dipole 10 m long lay on a flat surface of lunar soil, consisting of a layer of regolith 10 m thick and solid bedrock. The dipole parameters were determined by full-wave simulation using the Altair Feko 2022 software. The preamplifier was a single-stage HEMT low-noise amplifier, whose parameters were determined using the Advanced Design System 2023 software. An active antenna was analyzed using a model created to calculate all electrical and noise parameters. Special attention was paid to the analysis of the antenna sensitivity in terms of the System Equivalent Flux Density (SEFD) and Sky Noise Dominance (SND), taking into account changes in the lunar ambient temperature from 100 K to 400 K. It was shown that the frequency dependences of many active antenna parameters, in particular, radiation efficiency, directivity, effective area, SND, and SEFD had noticeable oscillatory components. The radiation pattern of the antenna was also subject to cyclical changes that occur in sync with the changes in directivity. These properties of the active antenna, caused by the presence of two-layer soil, should be considered when developing future lunar VLF radio telescopes.

Ephemeral Fast Radio Bursts (FRBs) must be powered by some of the most energetic processes in the Universe. That makes them highly interesting in their own right, and as precise probes for estimating cosmological parameters. This field thus poses a unique challenge: FRBs must be detected promptly and immediately localised and studied based only on that single millisecond-duration flash. The problem is that the burst occurrence is highly unpredictable and that their distance strongly suppresses their brightness. Since the discovery of FRBs in single-dish archival data in 2007, detection software has evolved tremendously. Pipelines now detect bursts in real time within a matter of seconds, operate on interferometers, buffer high-time and frequency resolution data, and issue real-time alerts to other observatories for rapid multi-wavelength follow-up. In this paper, we review the components that comprise a FRB search software pipeline, we discuss the proven techniques that were adopted from pulsar searches, we highlight newer, more efficient techniques for detecting FRBs, and we conclude by discussing the proposed novel future methodologies that may power the search for FRBs in the era of big data astronomy.

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.

Abstract The low‐latitude ionosphere is a dynamic region with a wide range of disturbances in temporal and spatial scales. The Giant Metrewave Radio Telescope (GMRT) situated in the low‐latitude region has demonstrated its ability to detect various ionospheric phenomena. It can detect total electron content (TEC) variation with precision of 10−3 TECU and also can measure TEC gradient with an accuracy of about 7 × 10−4 TECU km−1. This paper describes the spectral analysis of previously calculated TEC gradient measurements and validates them by comparing their properties using two bands. The analysis tracked individual waves associated with medium‐scale traveling ionospheric disturbances (MSTIDs) and smaller waves down to wavelengths of ∼10 km. The ionosphere is found to have unanticipated changes during sunrise hours, with waves changed propagation direction as the sun approached the zenith. Equatorial spread F disturbances during sunrise hours is observed, along with smaller structures moving in the same direction.

The precision and the reliability of very long baseline interferometry (VLBI) depend on several factors. Apart from fabrication discrepancies or meteorological effects, gravity-induced deformations of the receiving unit of VLBI radio telescopes are identified as a crucial error source biasing VLBI products and obtained results such as the scale of a realized global geodetic reference frame. Gravity-induced deformations are systematical errors and yield signal path variations (SPVs). In 1988, Clark and Thomsen derived a VLBI delay model, which was adopted by the International VLBI Service for Geodesy and Astrometry (IVS) to reduce these systematic errors. However, the model parametrizes the SPV by a linear substitute function and considers only deformations acting rotationally symmetrically. The aim of this investigation is to derive the signal path variations of a legacy radio telescope and a modern broadband VGOS-specified radio telescope and to study the effect of nonrotationally symmetric deformation patterns. For that purpose, SPVs are obtained from a nonlinear spatial ray tracing approach. For the first time, a tilt and a displacement of the subreflector perpendicular to the optical axis of the feed unit is taken into account. The results prove the commonly used VLBI delay model as a suitable first-order delay model to reduce gravity-induced deformations.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest and most sensitive single-dish radio telescope in the world and has made many important scientific achievements in a few years. Given the enormous scientific research potential of the Milky Way center, it is necessary to enhance the observation zenith angle as close to the Milky Way center as possible. In this regard, a new mechanism for the feed cabin is proposed with cables and sliders, which is lighter in weight and larger in the workspace. This paper will introduce this new feed cabin and the whole feed support system and establish their mechanical models to optimize the relevant control parameters, making FAST achieve an observation zenith angle of at least 50° with satisfying the required constraints. It indicates that the new mechanism designed by the FAST team can be used for the FAST upgrade and the future FAST array project. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 radio telescope 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. [ABSTRACT FROM AUTHOR]

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The dynamic response of a radio telescope structure under wind load excitation significantly impacts the accuracy of signal reception. To address this issue, this study established a parametric finite element model of a radio telescope to simulate its dynamic response under wind load excitation. An improved Latin hypercube sampling method was applied in the design of experiments (DOEs) to optimize the structural dimensional parameters of various components of the radio telescope with the aim of reducing the dynamic response to wind load. A response surface model and multi-objective genetic algorithm (MOGA) were employed for multi-objective structural optimization of the radio telescope structure. The findings reveal that the thickness of the stiffening ribs, the length of the side of the square hollow pole, the thickness of the middle pole, and the inner diameter of the thin pole are the most influential structural parameters affecting the first-order frequency (F1), second-order frequency (F2), maximum deformation in the x-direction (DX), and maximum deformation in the z-direction (DZ) of the radio telescope, respectively. Optimizing the radio telescope results in a 40.00% improvement in F1 and a 24.16% enhancement in F2, while reducing DX by 43.94% and DZ by 64.25%. The study outcomes offer a comprehensive scheme for optimizing the structural dimensional parameters of various radio telescope components in regions characterized by multiple wind fields.

Low-frequency aperture arrays represent sensitive instruments to detect signals from radio astronomic sources situated in the universe. In Italy, the Sardinia Aperture Array Demonstrator (SAAD) consists of an ongoing project of the Italian National Institute for Astrophysics (INAF) aimed to install an aperture array constituted of 128 dual-polarized Vivaldi antennas at the Sardinia Radio Telescope (SRT) site. The originally envisaged 128 elements of SAAD were re-scoped to the 16 elements of its precursor named SADino, with the aim to quickly test the system with a digital beam-former based on the Italian Tile Processing Module (iTPM) digital back-end. A preliminary measurements campaign of radio frequency interference (RFI) was performed to survey the less contaminated spectral region. The results of these measurements permitted the establishment of the technical requirements for receiving a chain for the SADino telescope. In this paper, the design, implementation, and characterization of this signal acquisition chain are proposed. The operative frequency window of SAAD and its precursor, SADino, sweeps from 260 MHz to 420 MHz, which appears very attractive for radio astronomy applications and radar observation in space and surveillance awareness (SSA) activities.

The search for technosignatures from hypothetical galactic civilizations is going through a new phase of intense activity. For the first time, a significant fraction of the vast search space is expected to be sampled in the foreseeable future, potentially bringing informative data about the abundance of detectable extraterrestrial civilizations or the lack thereof. Starting from the current state of ignorance about the galactic population of nonnatural electromagnetic signals, we formulate a Bayesian statistical model to infer the mean number of radio signals crossing Earth, assuming either nondetection or the detection of signals in future surveys of the Galaxy. Under fairly noninformative priors, we find that not detecting signals within about 1 kly from Earth, while suggesting the lack of galactic emitters or at best the scarcity thereof, is nonetheless still consistent with a probability exceeding 10% that typically over [Formula: see text] signals could be crossing Earth, with radiated power analogous to that of the Arecibo radar, but coming from farther in the Milky Way. The existence in the Galaxy of potentially detectable Arecibo-like emitters can be reasonably ruled out only if all-sky surveys detect no such signals up to a radius of about 40 kly, an endeavor requiring detector sensitivities thousands times higher than those of current telescopes. Conversely, finding even one Arecibo-like signal within [Formula: see text] light years, a possibility within reach of current detectors, implies almost certainly that typically more than [Formula: see text] signals of comparable radiated power cross the Earth, yet to be discovered.

The flux densities and current spectra of plerions and combined supernova remnants (SNRs): 3C58, 3C144, G11.2–0.3, G21.5–0.9, and 3C396 are determined on an artificial moon (AM) flux scale. The radio emission variability of the objects on different time scales is studied by multiple measurements using the RT-32 radio telescope at the Svetloe Observatory, Institute of Applied Astronomy, Russian Academy of Sciences and by mutual comparisons of the published measurement data, which have been brought to a common system using the AM flux scale. The radio emission from the SNRs displays both slow evolutionary variations and rapid ones, nonstationary in time. The rapid variability of the SNRs has features that are similar to those observed during solar flares. This fact may testify to the identity of the physical mechanisms underlying the rapid variability of the radio emission from plerions and from the Sun. Field line reconnections are considered as such a common mechanism. [ABSTRACT FROM AUTHOR]

Radio frequency interference (RFI) represents all unwanted signals detected by radio receivers of a telescope. Unfortunately, the presence of RFI is significantly increasing with the technological development of wireless systems around the world. For this reason, RFI measurement campaigns are periodically necessary to map the RFI scenario around a telescope. The Sardinia Radio Telescope (SRT) is an Italian instrument that was designed to operate in a wide frequency band between 300 MHz and 116 GHz. One of the receivers of the telescope is a coaxial cryogenic receiver that covered a portion of the P and L bands (i.e., 305–410 MHz and 1300–1800 MHz) in its original version. Although the receiver was used for years to observe bright sources with sufficient results, its sub-bands can be redesigned considering the most recently evolved RFI scenario. In this paper, the results of a RFI measurement campaign are reported and discussed. On the basis of these results, the new sub-bands of the L-P receiver, together with the design of the new microwave filter selector block of the SRT receiver, are presented. In this way, SRT will cover up to 120 MHz and 460 MHz of −3 dB bandwidth at the P-band (290–410 MHz) and L-band (1320–1780 MHz), respectively. The bands of these filters are selected to reject the main RFI with high levels of amplitude and optimize the estimated antenna temperature and sensitivity of the receiver during the research activities, such as pulsar observations, very long baseline interferometer applications and spectroscopy science.

Purpose: The analytical review of the main results of research in the new direction of the low-frequency radio astronomy, the interstellar medium radio spectroscopy at decameter waves, which had led to astrophysical discovery, recording of the radio recombination lines in absorption for highly excited states of interstellar carbon atoms (more than 600). Design/methodology/approach: The UTR-2 world-largest broadband radio telescope of decameter waves optimally connected with the digital correlation spectrum analyzers has been used. Continuous modernization of antenna system and devices allowed increasing the analysis band from 100 kHzto 24 MHz and a number of channels from 32 to 8192. The radio telescope and receiving equipment with appropriate software allowed to have a long efficient integration time enough for a large line series simultaneously with high resolution, noise immunity and relative sensitivity. Findings: A new type of interstellar spectral lines has been discovered and studied, the interstellar carbon radio recombination lines in absorption for the record high excited atoms with principal quantum numbers greater than 1000. The line parameters (intensity, shape, width, radial velocity) and their relation ship with the interstellar medium physical parameters have been determined. The temperature of line forming regions is about 100 K, the electron concentration up to 0.1 cm–3 and the size of a line forming region is about 10 pc. For the first time, radio recombination lines were observed in absorption. They have significant broadening and are amplified by the dielectronic-like recombination mechanism and are also the lowest frequency lines in atomic spectroscopy. Conclusions: The detected low-frequency carbon radio recombination lines and their observations have become a new highly effective tool for the cold partially ionized interstellar plasma diagnostics. Using them allows obtaining the information which is not available with the other astrophysical methods. For almost half a century of their research, a large amount of hardware-methodical and astrophysical results have been obtained including a record number of Galaxy objects, where there levant lines have been recorded. The domestic achievements have stimulated many theoretical and experimental studies in other countries, but the scientific achievements of Ukrainian scientists prove the best prospects for further development of this very important area of astronomical science.

To achieve the maximum dynamic range of solar radio images obtained using aperture synthesis in relatively wide frequency bands 0.1−0.5 % of the operating frequency, it is necessary to compensate the signal propagation delays in the antenna receive path before calculating visibility functions (hereinafter visibilities). When visibilities are corrected without delay compensation, the signal-to-noise ratio decreases due to residual phase slopes in the receiving system bandwidth. In addition to enhancing dynamic range, preliminary compensation for delays simplifies real-time imaging — no antenna gain calibration is required to get a first approximation image. The requirements for the accuracy of antenna placement are also reduced — in contrast to the measurement of the phase visibility error, the measurement of the delay is actually not so critical to the antenna position errors that are larger than the operating wavelength. The instantaneous frequency band of the Siberian Radioheliograph, which determines the minimum step for measuring the phase slope, and hence the accuracy of determining the delay, is 10 MHz. At the speed of light in an optical fiber of ~0.7c, a step of 10 MHz makes it possible to unambiguously measure the difference between electrical lengths of cables up to 20 m and to correct antenna positions by radio observations, even if the error in the position of the antennas exceeds the operating wavelength. Correction of the band phase slopes during the observation time adapts the radio telescope to the temperature drift of delays and decreases antenna gain phase spread. This, in turn, leads to more stable solutions to systems of equations containing antenna gains as unknowns.

Modern astrophysics research has heavily relied on data measured from telescopes. Reasonable observational scheduling brings into play action on the output of highly sensitive data and utilization of telescopes. However, most existing observational scheduling methods aim to solve medium- to long-term problems with proposals as scheduled objects. Nevertheless, the Yunnan 40 m Radio Telescope (YRT40) has the requirements of short-term scheduling within a few days. In this paper, we present a time-dependent short-term observational scheduling method based on a genetic algorithm to achieve automatic scheduling of observation targets. We established a mathematical model of a multi-objective optimization with time dependence and the constraints of telescope hardware conditions with the aim of minimizing the slew time of the telescope and maximizing the scientific values of the targets. In the experiments, we adopted the actual observational targets of YRT40. The results from tests on the runtime of the telescope demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This article provides a case study of antenna control servo system development in the Department of Atomic Energy over the last five decades, starting with the pioneering efforts for Ooty Radio Telescope (1970) and Arvi Earth Station (1971). While tracing the evolution of technology, the challenges and motivations, we evaluate these efforts against the basic tenets espoused by Homi Bhabha and Vikram Sarabhai for the growth of science and technology in India, viz. self-reliance with commercial viability. [ABSTRACT FROM AUTHOR]

One of the key reasons for the deterioration of antenna pointing accuracy for radio telescopes is the deformation and tilt of antenna alidades, which primarily result from track unevenness and thermal gradients. A high-precision inclinometer measurement system is installed to investigate the tilt of the antenna alidade and the pointing errors caused thermally. An environment control box with a leveling base was designed to reduce the interference of the external environment, which proved to be effective in guaranteeing the zero-point stability and repeat accuracy of the inclinometer. The tilt of the alidade caused by the track unevenness was measured by a test of slowly rotating the antenna along the azimuth at windless nighttime. A 5-day antenna stationary test and a 48 h astronomical pointing error measurement were performed, which proved the inclinometer measurement system is capable of measuring the thermally induced inclinations with acceptable accuracy. Through a preliminary compensation experiment, the pointing error is compensated from 37″ to 12″, which shows that the application of the system has a good effect on improving the pointing accuracy of the antenna. The system with high measurement accuracy, good system stability, and low computational complexity, proves an effective tool for the radio telescope to solve the problem of real-time measurement and compensation for antenna pointing errors.

Electromagnetic radiation from human activities, known as man-made Radio Frequency Interference (RFI), adversely affects radio astronomy observations. In the vicinity of the Upgraded Giant Metrewave Radio Telescope (uGMRT) array, the sparking on power lines is the major cause of interference at observing frequencies less than 800 MHz. A real-time broadband RFI detection and filtering system is implemented as part of the uGMRT wideband signal processing backend to mitigate the effect of broadband RFI. Performance analysis techniques used for testing and commissioning the system for observations in the beamformer and correlator modes of the uGMRT are presented. The concept and implementation of recording simultaneous unfiltered and filtered data along with data analysis and interpretation is illustrated using an example. For the beamformer mode, spectrogram, single spectral channel, and its Fourier transform is used for performance analysis whereas, in the correlator mode, the cross-correlation function, closure phase, and visibilities from the simultaneously recorded unfiltered and filtered is carried out. These techniques are used for testing the performance of the broadband RFI filter and releasing it for uGMRT users. [ABSTRACT FROM AUTHOR]

We describe a new type of ultrawideband feed antenna based on nested coaxial waveguides. The feed is for radio astronomy applications and covers two closely spaced bands: 400–800 and 900–1800 MHz. New design techniques are described for a three-cavity choke, a wideband iris matching network, and printed circuit board (PCB) excitation structures. The design methods were developed to improve broadband impedance matching, to control radiation patterns, to separate bands, and to suppress unwanted waveguide modes. The feed has nearly constant beamwidth over the entire 4.5:1 frequency range and a stable phase center. On an $f/D=0.43$ reflector antenna, the aperture efficiency exceeds 70% and the phase efficiency exceeds 95%. Other features include low ohmic loss and a compact, lightweight, and low-cost structure. Experimental results are shown for a scaled prototype to verify the design methodology. The methods described are general and can be applied to continuous frequency coverage on reflectors of different geometries. [ABSTRACT FROM AUTHOR]

The Earth's ionosphere is a highly variable medium on a wide range of spatio-temporal scales. The responsiveness of plasma to the geomagnetic field and its changes gives rise to anisotropy, which may introduce wave-like characteristics while scanning the ionosphere with a line-of-sight towards a radio source. Previous studies of LOw Frequency ARray (LOFAR) calibration phase solutions report that the estimated beta parameter of a structure function calculated over 6–8 h of astronomical observation timespan has a range of values from 1.6 to 2.0, with an average of 1.89. Such difference between the observations could result from transient wave-like disturbances within the data. This study aims to present a method of signal processing of ionospheric calibration datasets that allows the extraction of a transient wave-like signal and discuss its possible origin. We use complex Morlet wavelet analysis applied to two 8 h observations corresponding to very quiet geomagnetic conditions. We find a wave-like signal in the interferometric Total Electron Content data even during periods of no geomagnetic activity. We suggest it results from the relative velocity changes between the LOFAR line-of-sight and a convection pattern in the ionospheric F layer. Establishing the relationship between quiet time ionosphere, geomagnetic field changes and LOFAR's calibration solutions may prove beneficial to determination of the dominant signals in the more disturbed conditions, which we leave for future study. [ABSTRACT FROM AUTHOR]

An updated, binary-coded message has been developed for transmission to extraterrestrial intelligences in the Milky Way galaxy. The proposed message includes basic mathematical and physical concepts to establish a universal means of communication followed by information on the biochemical composition of life on Earth, the Solar System's time-stamped position in the Milky Way relative to known globular clusters, as well as digitized depictions of the Solar System, and Earth's surface. The message concludes with digitized images of the human form, along with an invitation for any receiving intelligences to respond. Calculation of the optimal timing during a given calendar year is specified for potential future transmission from both the Five-hundred-meter Aperture Spherical radio Telescope in China and the SETI Institute's Allen Telescope Array in northern California to a selected region of the Milky Way which has been proposed as the most likely location for life to have developed. These powerful new beacons, the successors to the Arecibo radio telescope which transmitted the 1974 message upon which this expanded communication is in part based, can carry forward Arecibo's legacy into the 21st century with this equally well-constructed communication from Earth's technological civilization. [ABSTRACT FROM AUTHOR]