In this paper, based on electromagnetic topology theory, a hybrid method that combines the Baum-Liu-Tesche BLT equation and transfer function is proposed. In this method, the coupling path of the radio telescope is divided into strong coupling and weak coupling sub-paths, and the coupling intensity criterion is proposed by analyzing the conditions in which the BLT equation simplifies to a transfer function. According to the coupling intensity criterion, the topological model of a typical radio telescope system is established. The proposed method is used to solve the interference response of the radio telescope system by analyzing subsystems with different coupling modes separately and then integrating the responses of the subsystems as the response of the entire system.
The validity of the proposed method is verified numerically. The results indicate that the proposed method, compared with the direct solving method, reduces the difficulty and improves the efficiency of interference prediction. To select a design that will be able to achieve the SKA requirements, we need good models of the instrument and the observed sky.
This makes detailed SKA simulations a vital part of any design effort. In particular we simulate an SKA pathfinder consisting of small dishes with phased-array focal-plane arrays mounted at the primary focus, and show some of the instrumental effects expected and their impact on observations. CFRP solutions for the innovative telescopes design. The new frontiers of the research in the astronomic field require the use of more and more advanced high-performance structures.
Only an adequate technological innovation of conventional telescopes and radio-telescopes allow to obtain structures able to meet the new specification of the projects. Besides, technological innovation is founded not only on the identification of more and more sophisticated mechanisms and optical instruments, but also on the development of new materials and manufacturing processes for the entire structure that constitute an instrument such as a telescope or a radio-telescope. Among these materials, the use of the carbon fibre is highly important.
This material, which is already widely used in the aerospace and automotive fields, shall join also the astronomic field for ground instruments. Thanks to the experience acquired with instruments like ALMA, the industry of composites is now able to guarantee different solutions at relatively low costs that allow the instruments of new generation to move extremely important steps in the development of scientific research.
Not just materials, but also processes, through which the materials are worked and manufactured, are extremely important. The use of technologies, such as hand lay-up vacuum bag, compression moulding, table rolling of composite tubes, filament winding, poltrusion and Resin Transfer Moulding RTM , allow to identify the ideal solution both for big dimension objects, such as backup structure, main mirror structure of quadripod legs, and relatively small objects, such as actuators, adjusters system, etc.
The wide choice, concerning the use of composite materials, and their techniques of production, allow the technicians to satisfy the exigencies of astronomers be they addressed to simple control of the weights or of the stiffness of the structures, or to specific thermal behaviour of the piece itself.
The Sardinia Radio Telescope. From a technological project to a radio observatory. Prandoni, I. Its active surface, comprised of separate aluminium panels supported by electromechanical actuators, will allow us to observe at frequencies of up to GHz. The SRT was officially opened in September , upon completion of its technical commissioning phase. In this paper, we provide an overview of the main science drivers for the SRT, describe the main outcomes from the scientific commissioning of the telescope , and discuss a set of observations demonstrating the scientific capabilities of the SRT.
As a result, the overall telescope performance has been significantly improved. Methods: As part of the scientific commissioning activities, different observing modes were tested and validated, and the first astronomical observations were carried out to demonstrate the science capabilities of the SRT. In addition, we developed astronomer-oriented software tools to support future observers on site. In the following, we refer to the overall scientific commissioning and software development activities as astronomical validation. Results: The astronomical validation activities were prioritized based on technical readiness and scientific impact.
The highest priority was to make the SRT available for joint observations as. We describe the design and performance of the Engineering Development Array, which is a low-frequency radio telescope comprising dual-polarisation dipole antennas working as a phased array. The Engineering Development Array was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array precursor technology and expertise, specifically from the Murchison Widefield Array radio telescope. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the Engineering Development Array's receiver temperature as a function of frequency.
The Engineering Development Array is shown to be sky-noise limited over most of the frequency range measured between 60 and MHz. By using the Engineering Development Array in interferometric mode with the Murchison Widefield Array, we used calibrated visibilities to measure the absolute sensitivity of the array. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature. The results demonstrate the practicality and feasibility of using Murchison Widefield Array-style precursor technology for Square Kilometre Array-scale stations.
The modular architecture of the Engineering Development Array allows upgrades to the array to be rolled out in a staged approach. Future improvements to the Engineering Development Array include replacing the second stage beamformer with a fully digital system, and to transition to using RF-over-fibre for the signal output from first stage beamformers. Liverpool Telescope 2: beginning the design phase. Copperwheat, Christopher M. The telescope began routine science operations in , and currently seven simultaneously mounted instruments support a broad science programme, with a focus on transient followup and other time domain topics well suited to the characteristics of robotic observing.
We are entering a new era of time domain astronomy with new discovery facilities across the electromagnetic spectrum, and the next generation of optical survey facilities such as LSST are set to revolutionise the field of transient science in particular. The fully robotic Liverpool Telescope 2 will have a 4-metre aperture and an improved response time, and will be designed to meet the challenges of this new era. In this paper we provide an overview of the facility and an update on progress.
Engineering and science highlights of the KAT-7 radio telescope. Foley, A. This paper looks at the main engineering and. Solar observations with a low frequency radio telescope. We have set up a low frequency radio monitoring station for solar bursts at the Observatory of the Aristotle University in Thessaloniki. The station consists of a dual dipole phased array, a radio receiver and a dedicated computer with the necessary software installed.
It operates continuously, since July , at The system is properly calibrated, so that the recorded data are expressed in antenna temperature. Despite the high interference level of an urban region like Thessaloniki strong broadcasting shortwave radio stations, periodic experimental signals, CBs, etc , we have detected several low frequency solar radio bursts and correlated them with solar flares, X-ray events and other low frequency solar observations.
The received signal is monitored in ordinary ASCII format and as audio signal, in order to investigate and exclude man-made radio interference. In order to exclude narrow band interference and calculate the spectral indices of the observed events, a second monitoring station, working at 36 MHz, is under construction at the village of Nikiforos near the town of Drama, about km away of Thessaloniki.
Finally, we plan to construct a third monitoring station at 58 MHz, in Thessaloniki. This frequency was revealed to be relatively free of interference, after a thorough investigation of the region. Its goal is to directly image and spectroscopically characterize planetary systems in the habitable zone of Sun-like stars. Additionally, HabEx will perform a broad range of general astrophysics science enabled by to nm spectral range and 3 x 3 arc-minute FOV. The baseline HabEx telescope is a 4-meter off-axis unobscured three-mirror-anastigmatic, diffraction limited at nm with wavefront stability on the order of a few 10s of picometers.
This paper summarizes the opto-mechanical design of the HabEx baseline optical telescope assembly, including a discussion of how science requirements drive the telescope 's specifications, and presents analysis that the baseline telescope structure meets its specified tolerances. Habitable exoplanet imager optical telescope concept design. Its goal is to directly image and spectroscopically characterize planetary systems in the habitable zone of Sunlike stars. The baseline HabEx telescope is a 4-meter off-axis unobscured three-mirroranastigmatic, diffraction limited at nm with wavefront stability on the order of a few 10s of picometers.
Recently, Su et al. The SYZ telescope design consists of three aspheric mirrors with non-zero power, including a relay mirror below the primary mirror. SYZ design yields a good imaging quality and has a relatively flat field curvature at Nasmyth focus. We find that although a SYZ telescope yields a superb imaging quality over a large field of view, a two-mirror RC telescope design holds a higher overall throughput, a better diffraction-limited imaging quality in the central field of view FOV Propagation engineering in radio links design.
Propagation Engineering in Radio Link Design covers the basic principles of radiowaves propagation in a practical manner. This fundamental understanding enables the readers to design radio links efficiently. This book elaborates on new achievements as well as recently developed propagation models. This is in addition to a comprehensive overview of fundamentals of propagation in various scenarios. It examines theoretical calculations, approaches and applied procedures needed for radio links design.
The authors study and analysis of the main propagation phenomena and its mechanisms based on the recommendations of International Telecommunications Union, ITU. The book presents some illustration Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope.
Vacca, Valentina; Murgia, M. Govoni F. In this work, we present radio observations of this region taken with the Sardinia Radio Telescope. Two of the clusters in the field host a powerful radio halo sustained by violent ongoing mergers and provide direct proof of intra-cluster magnetic fields.
In order to investigate the presence of large-scale diffuse radio synchrotron emission in and beyond the galaxy clusters in this complex system, we combined the data taken at 1. We found 28 candidate new sources with a size larger and X-ray emission fainter than known diffuse large-scale synchrotron cluster sources for a given radio power. This new population is potentially the tip of the iceberg of a class of diffuse large-scale synchrotron sources associated with the filaments of the cosmic web.
In addition, we found in the field a candidate new giant radio galaxy. Mevius, M. San Pedro Martir Telescope : Mexican design endeavor. Toledo-Ramirez, Gengis K. The OAN-SPM has an altitude of meters above sea level; it is among the best location for astronomical observation in the world.
The TSPM will be suitable for general science projects intended to improve the knowledge of the universe established on the Official Mexican Program for Science, Technology and Innovation The telescope efforts are headed by two Mexican institutions in name of the Mexican astronomical community: the Universidad Nacional Autonoma de Mexico and the Instituto Nacional de Astrofisica, Optica y Electronica.
It is under development by Mexican scientists and engineers from the Center for Engineering and Industrial Development. M3 Engineering and Technology Corporation in charge of enclosure and building design. The TSPM will be designed to allow flexibility and possible upgrades in order to maximize resources. Its optical and mechanical designs are based upon those of the Magellan and MMT telescopes.
The telescope will be optimized from the near ultraviolet to the near infrared wavelength range 0. Later, four folded Cassegrain and. Radio frequency integrated circuit design for cognitive radio systems. This book fills a disconnect in the literature between Cognitive Radio systems and a detailed account of the circuit implementation and architectures required to implement such systems. Throughout the book, requirements and constraints imposed by cognitive radio systems are emphasized when discussing the circuit implementation details.
In addition, this book details several novel concepts that advance state-of-the-art cognitive radio systems. This is a valuable reference for anybody with background in analog and radio frequency RF integrated circuit design , needing to learn more about integrated circuits requirements and implementation for cognitive radio systems. This article considers the development of the structure of receivers for Russian radio telescopes.
The development of these radio telescopes is undertaken within the project for creating a Russian small-antenna-based radio interferometer of new generation. It is shown that for small antennas A new multi-band feed based on traveling wave resonators is used. It has small dimensions, low weight, and allows working with circular polarizations. Thus it can be placed into focal container and cooled with the LNA.
A sketch of the focal container, with traveling-wave-resonator feed, and calculations of the expected parameters of the multi-band receiver are presented. An efficient feedback calibration algorithm for direct imaging radio telescopes. We present the E-field Parallel Imaging Calibration EPICal algorithm, which addresses the need for a fast calibration method for direct imaging radio astronomy correlators. This can save orders of magnitude in computation cost for next generation arrays consisting of hundreds or thousands of antennas. However, because antenna signals are mixed in the imaging correlator without creating visibilities, gain correction must be applied prior to imaging, rather than on visibilities post-correlation.
We develop the EPICal algorithm to form gain solutions quickly and without ever forming visibilities. This method scales as the number of antennas, and produces results comparable to those from visibilities. We use simulations to demonstrate the EPICal technique and study the noise properties of our gain solutions, showing they are similar to visibility-based solutions in realistic situations.
By applying EPICal to 2 s of Long Wavelength Array data, we achieve a 65 per cent dynamic range improvement compared to uncalibrated images, showing this algorithm is a promising solution for next generation instruments. We show that LOFAR is able to determine differential ionospheric total electron content values with an accuracy better than 0. The measured average slope is 1.
The diffractive scale, i. A small diffractive scale is equivalent to high phase variability over the field of view as well as a short time coherence of the signal, which limits calibration and imaging quality. For the studied observations the diffractive scales at MHz vary between 3. Designing for cooperation at a Radio Station. We address computer support for work and its coordination in one of the radio channels of the Danish Broadcasting Corporation. Based upon ethnographically inspired analysis and participatory design techniques, we propose design solutions now implemented or under implementation.
We focus on cooper We focus It is equipped with a 2. 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. First results of observations of the Sun and of the centre of the Milky Way are presented. Full Text Available Studying the variability of polarized AGN jet emission in the radio band is crucial for understanding the dynamics of moving shocks as well as the structure of the underlying magnetic field.
The m Effelsberg Telescope is a high-quality instrument for studying the long-term variability of both total and polarized intensity as well as the electric-vector position angle. Since , the F-GAMMA program has been monitoring the linear polarized emission of roughly 60 blazars at 11 frequencies between 2.
Kinematics and physical conditions of H I in nearby radio sources. The last survey of the old Westerbork Synthesis Radio Telescope. We present an analysis of the properties of neutral hydrogen H I in nearby 0. The observations were carried out with the Westerbork Synthesis Radio Telescope as the last large project before the. IPS observation system for the Miyun 50 m radio telescope and its commissioning observation. Ground-based observation of Interplanetary Scintillation IPS is an important approach for monitoring solar wind. A ground-based IPS observation system has been newly implemented on a 50 m radio telescope at Miyun station, managed by the National Astronomical Observatories, Chinese Academy of Sciences.
This observation system has been constructed for the purpose of observing solar wind speed and the associated scintillation index by using the normalized cross-spectrum of a simultaneous dual-frequency IPS measurement. The system consists of a universal dual-frequency front-end and a dual-channel multi-function back-end specially designed for IPS.
After careful calibration and testing, IPS observations on source 3C B and 3C have been successfully carried out. The preliminary observation results show that this newly-developed observation system is capable of performing IPS observation.
The system's sensitivity for IPS observation can reach over 0. A new calibration model for pointing a radio telescope that considers nonlinear errors in the azimuth axis. A new calibration model of a radio telescope that includes pointing error is presented, which considers nonlinear errors in the azimuth axis. For a large radio telescope , in particular for a telescope with a turntable, it is difficult to correct pointing errors using a traditional linear calibration model, because errors produced by the wheel-on-rail or center bearing structures are generally nonlinear.
Fourier expansion is made for the oblique error and parameters describing the inclination direction along the azimuth axis based on the linear calibration model, and a new calibration model for pointing is derived. The new pointing model is applied to the 40m radio telescope administered by Yunnan Observatories, which is a telescope that uses a turntable. The results show that this model can significantly reduce the residual systematic errors due to nonlinearity in the azimuth axis compared with the linear model.
The Allen Telescope Array, a dish radio interferometer in Northern California is now being upgraded with new, more sensitive receivers covering 0. Leveraging this frequency coverage and wide field of view, the ATA is a unique and ideal instrument for the discovery and characterization of fast radio bursts FRBs, discovered at Parkes and Arecibo and other short-time domain radio phenomena. The field of view nearly 10 sq. The instantaneous wide-frequency range of the upgraded ATA receivers allows sensitive observations at 4 simultaneous frequency ranges for example, 0.go to link
Thermal Design and Thermal Behaviour of Radio Telescopes and Their Enclosures
The goal is to design a telescope whose effective IR emissivity is no more than 2 percent when the mirrors are clean. It will be devoted to the observation of gamma rays over a wide band of energy, from a few tens of GeV to more than TeV. Two sites are foreseen to view the whole sky where about telescopes , composed of three different classes, related to the specific energy region to be investigated, will be installed.
Due to the large number of SSTs, their unit cost is an important parameter.
The integration of this telescope is currently in progress. Since the early stages of mechanical design of SST-GATE, finite element method has been used employing shape and topology optimization techniques to help design several elements of the telescope. These techniques and the resulting mechanical design are detailed in this paper. We will also describe the finite element analyses carried out to calculate the mechanical deformations and the stresses in the structure under observing and survival conditions. The bit angle encoders have been upgraded to bit in azimuth and elevation axes.
The control system has been substantially improved, in order to account for a number of previously-neglected, astrometric effects that are relevant for milli-degree pointing. In the summer , as a result of maintenance works, the orientation of the secondary mirror has been slightly altered, which resulted in worsening of the pointing precision, much below the nominal telescope capabilities. In preparation for observations at the highest available frequency of GHz, we use One Centimeter Receiver Array OCRA , to take the most accurate pointing data ever collected with the telescope , and we analyze it in order to improve the pointing precision.
Lynch, Ryan S. We present results from eight months of Green Bank Telescope 8. We tracked the radio and X-ray flux density, polarization properties, profile evolution, rotation, and single-pulse behavior. We identified two main periods of activity. The first is characterized by approximately 5. Specifically, a third profile component emerged and the radio flux also became more variable. Bright single pulses are well described by a log-normal energy distribution at low energies, but with an excess at high energies.
A joint pulsar timing analysis of the radio and X-ray data shows a level of timing noise unprecedented in a radio magnetar, though during the time covered by the radio data alone the timing noise was at a level similar to that observed in other radio magnetars. While SGR J— is similar to other radio magnetars in many regards, it differs by having experienced a period of relative stability in the radio that now appears to have ended, while the X-ray properties evolved independently. Rayleigh beacon for measuring the surface profile of a radio telescope.
Millimeter-wavelength Rayleigh scattering from water droplets in a cloud is proposed as a means of generating a bright beacon for measuring the surface profile of a radio telescope. The key advantage of the beacon is that it can be used at any time, and positioned anywhere in the sky, as long as there are clouds. Analyzing the capability of a radio telescope in a bistatic space debris observation system. A bistatic space debris observation system using a radio telescope as the receiving part is introduced. The detection capability of the system at different working frequencies is analyzed based on real instruments.
The detection range of targets with a fixed radar cross section and the detection ability of small space debris at a fixed range are discussed. The simulations of this particular observation system at different transmitting powers are also implemented and the detection capability is discussed. The simulated results approximately match the actual experiments. The analysis in this paper provides a theoretical basis for developing a space debris observation system that can be built in China.
Optical design trades are underway at the Goddard Space Flight Center to define a telescope for an x-ray survey mission. Top-level science objectives of the mission include the study of x-ray transients, surveying and long-term monitoring of compact objects in nearby galaxies, as well as both deep and wide-field x-ray surveys. In this paper we consider Wolter, Wolter-Schwarzschild, and modified Wolter-Schwarzschild telescope designs as basic building blocks for the tightly nested survey telescope.
Design principles and dominating aberrations of individual telescopes and nested telescopes are discussed and we compare the off-axis optical performance at 1. Have you ever wondered what it might be like to place control of a six-story building in the hands of eager high school students? This telescope is equipped with an X-band receiver, capable of observing center frequencies from GHz and is the first radio telescope accessible by students and observers through the SKYNET telescope network.
Operated remotely with a queue-based system, students can now collect real radio data for any range of projects. This past summer, five lessons were written that were tailor-made for student exploration of radio astronomy. Each lesson explores various radio objects in the context of an action-packed sci-fi adventure. Topics that are normally difficult to discuss with students in an inquiry-based classroom setting, such as HII regions, synchrotron radiation, lunar temperature profiles, and galactic supermassive black holes were addressed in the classroom using the lessons developed by the author for the 20m as well as data collected by students using the telescope via SKYNET.
Top-level science goals of the Survey and Time-domain Astrophysical Research eXplorer STAR-X include: investigations of most violent explosions in the universe, study of growth of black holes across cosmic time and mass scale, and measure how structure formation heats majority of baryons in the universe. To meet these goals, the field-of-view of the telescope should be about 1 square-degree, the angular resolution should be 5 arc-seconds or below across large part of the field-of-view. The on-axis effective area at 1 KeV should be about 2, sq cm. Payload cost and launch considerations limit the outer diameter, focal length, and mass to 1.
The telescope shells are divided into degree segments. Individual telescopes and meta-shells are nested inside each other to meet the effective area requirements in 0. These designs offer an excellent resolution over a large field of views. Nested telescopes are vulnerable to stray light problems. We have designed a multi-component baffle system to eliminate direct and single-reflection light paths inside the telescopes. Large number of internal and external baffle vane structures are required to prevent stray rays from reaching the focal plane. We have developed a simple ray-trace based tool to determine the dimensions and locations of the baffles.
In this paper, we present the results of our trade studies, baffle design studies, and optical performance analyses of the STAR-X telescope. Developments of next generation monitor and control systems for radio telescopes. As part of the ongoing upgrade of the GMRT observatory, the monitor and control M and C system is being upgraded to a modern specification driven system. The basic building block of the proposed M and C framework is a SACE node which provides command, response and event data streaming interfaces to the child and parent nodes running locally or remotely in a heterogeneous operating system environment.
For the recently built 15m antenna at NCRA, a generic, web based M and C system has been developed which allows remote, authenticated operation. We discuss issues relevant to the development of the next generation M and C systems for radio telescopes using the lessons learned from these two systems. We also summarize flexible, reusable and cost-effective approaches using off the shelf packages and technologies used in generic frameworks, which can contribute to form the basis for M and C systems of very large radio telescopes like the SKA.
Development of the Phase-up Technology of the Radio Telescopes : 6. For the sake of high-sensitivity 6. One is a VLBI method and the other is the newly developed digital position switching that is a similar technology to that used in noise-canceling headphones. A Q-band two-beam cryogenic receiver for the Tianma Radio Telescope. The Q-band receiver consists of three parts: optics, cold unit assembly and warm unit assembly, and it can receive simultaneously the left-handed and right-handed circularly polarized waves.
The cold unit assembly of each beam is composed of a feed horn, a noise injection coupler, a differential phase shifter, an orthomode transducer and two low-noise amplifiers, and it works at a temperature range near 20 K to greatly improve the detection sensitivity of the receiving system. The warm unit assembly includes four radio -frequency amplifiers, four radio -frequency high-pass filters, four waveguide biased mixers, four 4—12 GHz intermediate-frequency amplifiers and one 31—38 GHz frequency synthesizer.
The measured Q-band four-channel receiver noise temperatures are roughly 30—40 K. Goullioud, R. This mission is based on a space telescope at L2 studying exoplanets [via gravitational microlensing], probing dark energy, and surveying the near infrared sky.
We present the current interim reference mission point design of the payload, based on the use of a 1. Polarimetry of pulsars from observations at 1. Over the past 13 yr, the Parkes radio telescope has observed a large number of pulsars using digital filter bank backends with high time and frequency resolution and the capability for Stokes recording. Here, we use archival data to present polarimetry data at an observing frequency of 1. We comment briefly on some of the statistical implications from the data and highlight the differences between pulsars with high and low spin-down energy.
The data set, images and table of properties for all pulsars are made available in a public data archive maintained by the CSIRO. The prospects of pulsar timing with new-generation radio telescopes and the Square Kilometre Array. Pulsars are highly magnetized and rapidly rotating neutron stars.
As they spin, the lighthouse-like beam of radio emission from their magnetic poles sweeps across the Earth with a regularity approaching that of the most precise clocks known. This precision combined with the extreme environments in which they are found, often in compact orbits with other neutron stars and white dwarfs, makes them excellent tools for studying gravity. These telescopes will also greatly improve the precision to which we can measure the arrival times of the pulses.
The Square Kilometre Array will revolutionize pulsar searches and timing precision. The increased number of sources will reveal rare sources, including possibly a pulsar-black hole binary, which can provide the most stringent tests of strong-field gravity. The improved timing precision will reveal new phenomena and also allow us to make a detection of gravitational waves in the nanohertz frequency regime.
It is here where we expect to see the signature of the binary black holes that are formed as galaxies merge throughout cosmological history.
- Woodworking Shopnotes Contents Index (1-81).
- The Third Reich Sourcebook (Weimar and Now: German Cultural Criticism).
- Recommended for you?
- Browse Search.
- Indian Philosophy (Volume 2).
- Textile Conservation?
- Albert Greve.
Harp, G. We characterize the antenna optical accuracy using two-antenna interferometry and radio holography. Holography provides images of dish illumination, characterizing as-built mirror surfaces. Experimental RMS errors are 0. ATA's wide-bandwidth receiver permits observations over a continuous range 0. We probe the antenna optical gain and beam pattern stability as a function of focus position and observation frequency, concluding that ATA can produce high fidelity images over a decade of simultaneous observation frequencies. We quantify solar heating effects on antenna sensitivity and pointing accuracy.
A high temperature superconductor notch filter for the Sardinia Radio Telescope. A High Temperature Superconductor filter operating in the C-band between and MHz has been developed for one of the radio astronomical receivers of the Sardinia Radio Telescope.
- Albert Greve.
- The fields are white.
- Rational Choice and Social Welfare: Theory and Applications Essays in Honor of Kotaro Suzumura.
The motivation was to attenuate an interference from a weather radar at MHz, whose power level exceeds the linear region of the first active stages of the receiver. A very sharp transition after the nominal maximum passband frequency is reached by combining a 6th order band-pass filter with a 6th order stop-band. This solution is competitive with an alternative layout based on a cascaded triplet filter. Three units of the filter have been measured with two different calibration approaches to investigate pros and cons of each, and data repeatability.
The final performance figures of the filters are: ohmic losses of the order of 0. Finally, a more accurate model of the connection between external connector and microstrip shows a better agreement between simulations and experimental data. Jet emission in young radio sources: A Fermi large area telescope gamma-ray view. Migliori, G. With ten giant dish antennas spread from Hawaii in the Pacific to St.
zewacekado.tk: Michael Bremer - Physics / Science, Nature & Math: Books
Croix in the Caribbean, all working together as a single telescope , the VLBA is "the world's biggest astronomical instrument," Vanden Bout said. The VLBA has been in full operation for more than five years. In more than 40 scientific presentations, astronomers tell how they used the VLBA to gain valuable new information about nearly every area from the frontiers of astrophysics.
D degrees. Radio astronomers have directly measured the distance to a faraway galaxy, providing a valuable "yardstick" for calibrating large astronomical distances and demonstrating a vital method that could help determine the elusive nature of the mysterious Dark Energy that pervades the Universe. The measurement highlights a valuable method that can be used to determine the local expansion rate of the Universe, which is essential in our quest to find the nature of Dark Energy," said James Braatz, of the National Radio Astronomy Observatory NRAO , who presented the work to the American Astronomical Society's meeting in Pasadena, California.
To do this, they precisely measured both the linear and angular size of a disk of material orbiting the galaxy's central black hole. Water molecules in the disk act as masers to amplify, or strengthen, radio waves the way lasers amplify light waves. The observation is a key element of a major effort to measure the expansion rate of the Universe, known as the Hubble Constant, with greatly improved precision.
That effort, cosmologists say, is the best way to narrow down possible explanations for the nature of Dark Energy. Tradespace investigation of strategic design factors for large space telescopes. Future large telescope arrays require careful balancing of satisfaction across the stakeholders' community. Development programs usually cannot afford to explicitly address all stakeholder tradeoffs during the conceptual design stage, but rather confine the analysis to performance, cost, and schedule discussions, treating policy and budget as constraints defining the envelope of the investigation.
Thus, it is of interest to develop an integrated stakeholder analysis approach to explicitly address the impact of all stakeholder interactions on the design of large telescope arrays to address future science and exploration needs. This paper offers a quantitative approach for modeling some of the stakeholder influences relevant to large telescope array designs -the linkages between a given mission and the wider NASA community.
The main goal of the analysis is to explore the tradespace of large telescope designs and understand the effects of different design decisions in the stakeholders' network. Proposed architectures that offer benefits to existing constellations of systems, institutions, and mission plans are expected to yield political and engineering benefits for NASA stakeholders' wider objectives. If such synergistic architectures are privileged in subsequent analysis, regions of the tradespace that better meet the needs of the wider NASA community can be selected for further development.
The goal to my research, therefore, was to accurately predict the exact locations of satellites in our sky to analyze specific satellites causing the interference as well as potentially predict when satellites will cross in the way of our beams so that we can further optimize our scripts and get more usable data.
I have built an algorithm that plots the exact location in altitude and azimuth of any grouping of satellites that you want in the sky from any position on earth in latitude, longitude, and elevation. From there, you can input a specific right ascension and declination of the location you are trying to track in the sky with a telescope. Using these inputs, we can calculate the angular and positional distance of certain satellites to our beam to further analyze satellite radio frequency interference. The process begins by importing a list of Two Line Element information that the algorithm reads in.
Two Line Elements are how Satellites are organized and are updated frequently. From there, the code breaks up the information given by these elements to predict their location. The algorithm can also plot in 3D coordinates around an earthlike sphere to conceptualize the route that each Satellite has taken. From here, the code will be the backbone to calculating drift rates, Doppler shifts and intensity of certain satellites and why our team consistently receives estranged satellite signals of interest.
Furthermore, in the case of a serious candidate signal in the near future, it will be important to analyze satellites interfering in the beam. Through our generic and efficient E-field Parallel Imaging Correlator epic , we present the first software demonstration of a generalized direct imaging algorithm, namely the Modular Optimal Frequency Fourier imager. We have verified the images produced to be equivalent to those from traditional techniques to within a precision set by gridding coarseness. We provide a detailed framework for imaging with heterogeneous arrays and show that epic robustly estimates the input sky model for such arrays.
Antenna layouts with dense filling factors consisting of a large number of antennas such as LWA, the Square Kilometre Array, Hydrogen Epoch of Reionization Array, and Canadian Hydrogen Intensity Mapping Experiment will gain significant computational advantage by deploying an optimized version of epic. The algorithm is a strong candidate for instruments targeting transient searches of fast radio bursts as well as planetary and exoplanetary phenomena due to the availability of high-speed calibrated time-domain images and low output bandwidth relative to visibility-based systems.
Optical telescope refocussing mechanism concept design on remote sensing satellite. The optical telescope system in remote sensing satellite must be precisely aligned to obtain high quality images during its mission life. In practical, because the telescope mirrors could be misaligned due to launch loads, thermal distortion on supporting structures or hygroscopic distortion effect in some composite materials, the optical telescope system is often equipped with refocussing mechanism to re-align the optical elements while optical element positions are out of range during image acquisition.
This paper is to introduce satellite Refocussing mechanism function model design development process and the engineering models. The design concept of the refocussing mechanism can be applied on either cassegrain type telescope or korsch type telescope , and the refocussing mechanism is located at the rear of the secondary mirror in this paper. The purpose to put the refocussing mechanism on the secondary mirror is due to its higher sensitivity on MTF degradation than other optical elements.
There are two types of refocussing mechanism model to be introduced: linear type model and rotation type model. For the linear refocussing mechanism function model, the model is composed of ceramic piezoelectric linear step motor, optical rule as well as controller. The secondary mirror is designed to be precisely moved in telescope despace direction through refocussing mechanism. For the rotation refocussing mechanism function model, the model is assembled with two ceramic piezoelectric rotational motors around two orthogonal directions in order to adjust the secondary mirror attitude in tilt angle and yaw angle.
From the validation test results, the linear type refocussing mechanism function model can be operated to adjust the secondary mirror position with minimum nm resolution with close loop control. The GOES Telescope utilizes a flexure mounting system for the secondary mirror to minimize thermally induced distortions of the secondary mirror.
The detailed design is presented along with a discussion of the microradian pointing requirements and how they were achieved. The research councils discovered in December the allocation of money from the UK government's Comprehensive Spending Review, and have set out their delivery plans outlining how they will spend it.
Details and decisions will follow consultation in the coming months. The first image from eMerlin, the UK's national radio astronomy facility, shows the power of the enhanced network of radio telescopes spread over km and now linked by fibre optics. These links and advanced receivers will allow astronomers to see in a single day what would have previously taken them more than a year of observations.
A 20m telescope is outfitted with cryogenically cooled receivers and a reprogrammable spectrometer. This is accomplished through the capabilities to use existing observing modes and through reprogram the University of California, Berkeley's Field Programmable Gate Array FPGA systems for custom digital hardware development. This provides a door for engineering and computer science students to create real-time, high capability data acquisition and processing tools.
We will demo the 20m observing system and its capabilities. The NSF funded this construction project with the goal of making the network self funding. We are looking for collaborators with targeted research projects wanting to take advantage of the powerful observing tools. Scientists present their design for Einstein Telescope. Plans shape up for a revolutionary new observatory that will explore black holes and the Big Bang.
A new era in astronomy will come a step closer when scientists from across Europe present their design study today for an advanced observatory capable of making precision measurements of gravitational waves — minute ripples in the fabric of spacetime — predicted to emanate from cosmic catastrophes such as merging black holes and collapsing stars and supernovae. It also offers the potential to probe the earliest moments of the Universe just after the Big Bang, which are currently inaccessible. The Einstein Observatory ET is a so-called third-generation gravitational-wave GW detector, which will be times more sensitive than current instruments.
Like the first two generations of GW detectors, it is based on the measurement of tiny changes far less than the size of an atomic nucleus in the le The Hubble Space Telescope nickel-hydrogen battery design. Details are presented of the HST Hubble Space Telescope battery cell, battery package, and module mechanical and electrical designs.
Also included are a summary of acceptance, qualification, and vibration tests and thermal vacuum testing. Unique details of battery cell charge retention performance characteristics associated with prelaunch hold conditions are discussed. Special charge control methods to minimize thermal dissipation during pad charging operations are summarized. This module design meets all NASA fracture control requirements for manned missions.
Design and manufacturing of the CFRP lightweight telescope structure. Design of earthbound telescopes is normally based on conventional steel constructions. Several years ago thermostable CFRP Telescope and reflector structures were developed and manufacturing for harsh terrestrial environments. The airborne SOFIA TA requires beyond thermostability an excessive stiffness to mass ratio for the structure fulfilling performance and not to exceed mass limitations by the aircraft Boeing SP.
Thickness of CFRP Laminates, either filament wound or prepreg manufactured need special attention and techniques to gain high material quality according to aerospace requirements. Sequential shop assembly of the structure subassemblies minimizes risk for assembling TA. Design goals, optimization of layout and manufacturing techniques and results are presented. Design of ultra-low power impulse radios. This book covers the fundamental principles behind the design of ultra-low power radios and how they can form networks to facilitate a variety of applications within healthcare and environmental monitoring, since they may operate for years off a small battery or even harvest energy from the environment.
These radios are distinct from conventional radios in that they must operate with very constrained resources and low overhead. This book provides a thorough discussion of the challenges associated with designing radios with such constrained resources, as well as fundamental design concepts and practical approaches to implementing working designs. Novel measurement-based indoor cellular radio system design.
A scaleable, measurement-based radio methodology has been created to use for the design , planing and optimisation of in door cellular radio systems. The development of this measurement-based methodology was performed having in mind that measurements are of ten required to valiate radio coverage in a building. Therefore, the concept of using care fully calibrated measurements to design and optimise a system is feasible since these measurements can easily be obtained prior to system deployment Schinzel, Frank K.
Bhatnagar, S. This paper is concerned with algorithms for calibration of direction-dependent effects DDE in aperture synthesis radio telescopes ASRT. After correction of direction-independent effects DIE using self-calibration, imaging performance can be limited by the imprecise knowledge of the forward gain of the elements in the array. In general, the forward gain pattern is directionally dependent and varies with time due to a number of reasons.
Some factors, such as rotation of the primary beam with Parallactic Angle for Azimuth—Elevation mount antennas are known a priori. Thus, in addition to algorithms to correct for DD effects known a priori, algorithms to solve for DD gains are required for high dynamic range imaging. Here, we discuss a mathematical framework for antenna-based DDE calibration algorithms and show that this framework leads to computationally efficient optimal algorithms that scale well in a parallel computing environment.
As an example of an antenna-based DD calibration algorithm, we demonstrate the Pointing SelfCal PSC algorithm to solve for the antenna pointing errors. Our analysis show that the sensitivity of modern ASRT is sufficient to solve for antenna pointing errors and other DD effects. We also discuss the use of the PSC algorithm in real-time calibration systems and extensions for antenna Shape SelfCal algorithm for real-time tracking and corrections for pointing offsets and changes in antenna shape. Some factors, such as rotation of the primary beam with Parallactic Angle for Azimuth-Elevation mount antennas are known a priori.
Leo T is the lowest mass gas-rich galaxy currently known and studies of its gas content help us understand how such marginal galaxies survive and form stars. We present deep neutral hydrogen H I observations from the Westerbork Synthesis Radio Telescope in order to understand its H I distribution and potential for star formation. The additional H I flux is from low surface brightness emission that was previously missed; with careful masking this emission can be recovered even in shallower data. We perform a Gaussian spectral decomposition to find a cool neutral medium component CNM with a mass of 3.
Leo T has no H I emission extending from the main H I body, but there is evidence of interaction with the Milky Way circumgalactic medium in both a potential truncation of the H I body and the offset of the peak H I distribution from the optical center. The CNM component of Leo T is large when compared to other dwarf galaxies, even though Leo T is not currently forming stars and has a lower star formation efficiency than other gas-rich dwarf galaxies. One possible explanation is the large CNM component is not related to star formation potential but rather a recent, transient phenomenon related to the interaction of Leo T with the Milky Way circumgalactic medium.
Recently, Cognitive Radio has been proposed as a promising technology to improve spectrum utilization. A highly flexible OFDM system is considered to be a good candidate for the Cognitive Radio baseband processing where individual carriers can be switched off for frequencies occupied by a licensed.
Preliminary design study of the TMT Telescope structure system: overview. Design optimizations were pursued to better meet the design requirements and improvements were made in the designs of many of the telescope subsystems as follows: 1. M1 Segment Handling System SHS to be able to make removing and installing 10 Mirror Segment Assemblies per day safely and with ease over M1 area where access of personnel is extremely difficult. This requires semi-automatic sequence operation and a robotic Segment Lifting Fixture SLF designed based on the Compliance Control System, developed for controlling industrial robots, with a mechanism to enable precise control within the six degrees of freedom of position control.
CO2 snow cleaning system to clean M1 every few weeks that is similar to the mechanical system that has been used at Subaru Telescope. Seismic isolation and restraint systems with respect to safety; the maximum acceleration allowed for M1, M2, tertiary mirror M3 , LGSF, and science instruments in 1, year return period earthquakes are defined in the requirements. The Seismic requirements apply to any EL angle, regardless of the. Guillemot, L. The new pulsar, confirmed with the Green Bank Telescope , has a spin period of 2. However, NDL India takes no responsibility for, and will not be liable for, the portal being unavailable due to technical issues or otherwise.
For any issue or feedback, please write to ndl-support iitkgp. Access Restriction Subscribed. Log-in to view content. FAQ Help. Member Log-In. E-mail address. Remember me. Account recovery. You are in page, help us by providing your feedback on different features. Select feature Accessibility Type Metadata. Select feature Registration Log-in Account recovery Profile customization.