The Five-hundred-meter Aperture Spherical radio Telescope (FAST) passed national acceptance and is taking pilot cycle of 'Shared-Risk' observations. The 19-beam receiver covering 1.05-1.45 GHz was used for most of these observations. The electronics gain fluctuation of the system is better than 1\% over 3.5 hours, enabling enough stability for observations. Pointing accuracy, aperture efficiency and system temperature are three key parameters of FAST. The measured standard deviation of pointing accuracy is 7.9$''$, which satisfies the initial design of FAST. When zenith angle is less than 26.4$^\circ$, the aperture efficiency and system temperature around 1.4 GHz are $\sim$ 0.63 and less than 24 K for central beam, respectively. The measured value of these two parameters are better than designed value of 0.6 and 25 K, respectively. The sensitivity and stability of the 19-beam backend are confirmed to satisfy expectation by spectral HI observations toward N672 and polarization observations toward 3C286. The performance allows FAST to take sensitive observations in various scientific goals, from studies of pulsar to galaxy evolution.
We have developed a two-beam waveguide-type dual-polarization sideband-separating SIS receiver system in the 100-GHz band for {\it z}-machine on the 45-m radio telescope at the Nobeyama Radio Observatory. The receiver is intended for astronomical use in searching for highly redshifted spectral lines from galaxies of unknown redshift. This receiver has two beams, which have 45$^{\prime\prime}$ of beam separation and allow for observation with the switch in the on-on position. The receiver of each beam is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both…
We have developed a 230 and 345 GHz very-long-baseline interferometry (VLBI) receiver for the South Pole Telescope (SPT). With the receiver installed, the SPT has joined the global Event Horizon Telescope (EHT) array. The receiver optics select the 230 or 345 GHz mixers by rotating the tertiary mirror around the optical axis, directing the chief ray from the secondary mirror to the feed horn of the selected frequency band. The tertiary is installed on top of the receiver cryostat, which contains both mixer assemblies. The feed horns are placed symmetrically across the centerline of the telesco…
A method for accurate modeling of a reflector antenna system with a wideband phased array feed is presented and used to study the effects of the number of active antenna elements and associated receiving channels on the receiving sensitivity of the antenna system. Numerical results are shown for a practical design named APERTIF that is currently under developed at The Netherlands Institute for Radio Astronomy (ASTRON).
A method for modeling a reflector antenna system with a wideband phased array feed is presented and used to study the effects of the number of active antenna elements and associated receiving channels on the sensitivity of the system. Numerical results are shown for a practical system named APERTIF that is currently under developed at The Netherlands Institute for Radio Astronomy (ASTRON)
We report the current status of the NASCO (NAnten2 Super CO survey as legacy) project which aims to provide all-sky CO data cube of southern hemisphere using the NANTEN2 4-m submillimeter telescope installed at the Atacama Desert through developing a new multi-beam receiver and a new telescope control system. The receiver consists of 5 beams. The four beams, located at the four corners of a square with the beam separation of 720$''$, are installed with a 100 GHz band SIS receiver having 2-polarization sideband-separation filter. The other beam, located at the optical axis, is installed with a …
The calibration procedures for data collected for Argus and the 4mm Receiver instruments on the GBT are presented. The measured beam size, aperture efficiency, and main-beam efficiency are derived for the range of observing frequencies (66--116 GHz) within the 3mm atmospheric window. The telescope performs well even at the highest frequencies (>100 GHz). The amount of power in the error pattern of the antenna beam is estimated. Approximately 95% of the total antenna power is contained within 1 degree of the pointed direction. The calibration derived using small sources follows theoretical expe…
We present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16-50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by $λ$/$D$ over the frequency range with a correlation coefficient of ~90%. We determine the telescope main beam efficiencies are between ~48-64% for the 12-mm receiver an…
We developed a dual-linear-polarization HEMT (High Electron Mobility Transistor) amplifier receiver system of the 45-GHz band (hereafter Z45), and installed it in the Nobeyama 45-m radio telescope. The receiver system is designed to conduct polarization observations by taking the cross correlation of two linearly-polarized components, from which we process full-Stokes spectroscopy. We aim to measure the magnetic field strength through the Zeeman effect of the emission line of CCS ($J_N=4_3-3_2$) toward pre-protostellar cores. A linear-polarization receiver system has a smaller contribution of …
We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300K and 2) the beam pattern expected from the rece…
The digital record of the voltage in a radio telescope receiver, after frequency conversion and sampling at a finite rate, is not a perfect representation of the original analog signal. To detect and characterise a transient event with a duration comparable to the inverse bandwidth it is necessary to compensate for these effects, which modifies the statistics of the signal, making it difficult to determine the significance of a potential detection. We present an analysis of these modified statistics and demonstrate them with experimental results from Bedlam, a new digital backend for the Parke…
This paper presents an ultra-low noise L-band radio astronomical cryogenic receiver for FAST telescope. The development of key low noise microwave parts of Coupling-LNA and conical quad-ridge OMT and reasonable system integration achieve outstanding performance of receiver.It covers the frequency range of 1.2 GHz to 1.8 GHz. Novel cryogenic Coupling-LNAs with low noise, large return loss, high dynamic range and the function of coupling calibration signals are developed for the proposed receiver.Amplification and coupling function circuits are integrated as a single Coupling-LNA with full noise…
We present a conceptual design for the input optical system for a multi-object spectrometer operating at submillimeter wavelengths. The Mirror MOS is based on a sequence of mirrors that enables low-loss propagation of beams from selected positions distributed throughout the focal plane to the spectroscopic receiver inputs. This approach should be useful for observations of sources which have a relatively low density on the sky, for which it is inefficient to use a traditional array receiver with uniformly spaced, relatively closely packed beams. Our concept is based on assigning a patrol regio…
The purpose of this report is to document the noise performance of a complex beamforming array antenna system and to characterize the recently developed noise measurement facility called THACO, which was developed at ASTRON. The receiver system includes the array antenna of strongly coupled 144 TSA elements, 144 Low Noise Amplifiers (LNAs) (Tmin =35-40K) and the data recording/storing facilities of the initial test station that allow for off-line digital beamforming. The primary goal of this study is to compare the measured receiver noise temperatures with the simulated values for several prac…
We describe the design, construction, and characterization of the Band 9 heterodyne receivers (600-720 GHz) for the Atacama Large Millimeter / submillimeter Array (ALMA). The ALMA Band 9 receiver units ("cartridges"), which are installed in the telescope's front end, have been designed to detect and down-convert two orthogonal linear polarization components of the light collected by the ALMA antennas. The light entering the front end is refocused with a compact arrangement of mirrors, which is fully contained within the cartridge. The arrangement contains a grid to separate the polarizations a…
With a collecting area of 70 000 m^2, the Five hundred metre Aperture Spherical Telescope (FAST) will allow for great advances in pulsar astronomy. We have performed simulations to estimate the number of previously unknown pulsars FAST will find with its 19-beam or possibly 100-beam receivers for different survey strategies. With the 19-beam receiver, a total of 5200 previously unknown pulsars could be discovered in the Galactic plane, including about 460 millisecond pulsars (MSPs). Such a survey would take just over 200 days with eight hours survey time per day. We also estimate that, with ab…
A new 1.4 GHz 19-element, dual-polarization, cryogenic phased array feed (PAF) radio astronomy receiver has been developed for the Robert C. Byrd Green Bank Telescope (GBT) as part of FLAG (Focal L-band Array for the GBT) project. Commissioning observations of calibrator radio sources show that this receiver has the lowest reported beamformed system temperature ($T_{\rm sys}$) normalized by aperture efficiency ($η$) of any phased array receiver to date. The measured $T_{\rm sys}/η$ is $25.4 \pm 2.5$ K near 1350 MHz for the boresight beam, which is comparable to the performance of the current 1…
Systematic effects in dual-beam, differential, radio observations of extended objects are discussed in the context of the One Centimeter Receiver Array (OCRA). We use simulated samples of Sunyaev-Zel'dovich (SZ) galaxy clusters at low ($z<0.4$) and intermediate ($0.4<z<1.0$) redshifts to study the implications of operating at a single frequency (30 GHz) on the accuracy of extracting SZ flux densities and of reconstructing comptonization parameters with OCRA. We analyze dependences on cluster mass, redshift, observation strategy, and telescope pointing accuracy. Using $Planck$ data to make prim…
This thesis focuses on the two main applications where free-space optical communication (FSOC) can bring the most significant impact: interplanetary communications and quantum communications. Consequently, the dissertation is structured in two sections. In the first one, a novel proposal is suggested regarding to using Cherenkov telescopes as ground-station receivers. A feasibility study addresses the posibility of using the technology developed for the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) in the implementation of a new kind of ground station. Among the ma…
If fast radio bursts (FRBs) originate from galaxies at cosmological distances, then their all-sky rate implies that the Milky Way may host an FRB on average once every 30-1500 years. If FRBs repeat for decades or centuies, a local FRB could be active now. A typical Galactic FRB would produce a millisecond radio pulse with ~1 GHz flux density of ~3E10 Jy, comparable to the radio flux levels and frequencies of cellular communication devices (cell phones, Wi-Fi, GPS). We propose to search for Galactic FRBs using a global array of low-cost radio receivers. One possibility is to use the ~1GHz commu…
