Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDevelopment of the new multi-beam receiver and telescope control system for NASCO
486
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
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 200 GHz band SIS receiver having 2-polarization sideband-separation filter. The cooled component is modularized for each beam, and cooled mirrors are used. The IF bandwidths are 8 and 4 GHz for 100 and 200 GHz bands, respectively. Using XFFTS spectrometers with a bandwidth of 2 GHz, the lines of $^{12}$CO, $^{13}$CO, and C$^{18}$O of $J$=1$-$0 or $J$=2$-$1 can be observed simultaneously for each beam. The control system is reconstructed on the ROS architecture, which is an open source framework for robot control, to enable a flexible observation mode and to handle a large amount of data. The framework is commonly used and maintained in a robotic field, and thereby reliability, flexibility, expandability, and efficiency in development are improved as compared with the system previously used. The receiver and control system are installed on the NANTEN2 telescope in December 2019, and its commissioning and science verification are on-going. We are planning to start science operation in early 2021.
rate research
Read More
We have developed a wideband receiver system for simultaneous observations in CO lines of J = 2-1 and J = 3-2 transitions using the Osaka 1.85-m mm-submm telescope. As a frequency separation system, we developed multiplexers that connect three types of diplexers, each consisting of branch-line couplers and high-pass filters. The radio frequency (RF) signal is eventually distributed into four frequency bands, each of which is fed to a superconductor-insulator-superconductor (SIS) mixer. The RF signal from the horn is divided into two frequency bands by a wideband diplexer with a fractional bandwidth of 56%, and then each frequency band is further divided into two bands by each diplexer. The developed multiplexers were designed, fabricated, and characterized using a vector network analyzer. The measurement results showed good agreement with the simulation. The receiver noise temperature was measured by connecting the SIS-mixers, one of which has a wideband 4-21GHz intermediate frequency (IF) output. The receiver noise temperatures were measured to be ~70K in the 220GHz band, ~100K in the 230GHz band, 110-175K in the 330GHz band, and 150-250K in the 345GHz band. This receiver system has been installed on the 1.85-m telescope at the Nobeyama Radio Observatory. We succeeded in the simultaneous observations of six CO isotopologue lines with the transitions of J = 2-1 and J = 3-2 toward the Orion KL as well as the on-the-fly (OTF) mappings toward the Orion KL and W 51.
The corrugated horn is a high performance feed often used in radio telescopes. There has been a growing demand for wideband optics and corrugated horns in millimeter and submillimeter-wave receivers. It improves the observation efficiency and allows us to observe important emission lines such as CO in multiple excited states simultaneously. However, in the millimeter/submillimeter band, it has been challenging to create a conical corrugated horn with a fractional bandwidth of ~60% because the wavelength is very short, making it difficult to make narrow corrugations. In this study, we designed a conical corrugated horn with good return loss, low cross-polarization, and symmetric beam pattern in the 210-375GHz band (56% fractional bandwidth) by optimizing the dimensions of the corrugations. The corrugated horn was installed on the Osaka 1.85-m mm-submm telescope with the matched frequency-independent optics, and simultaneous observations of 12CO, 13CO, and C18O (J = 2-1, 3-2) were successfully made. In this paper, we describe the new design of the corrugated horn and report the performance evaluation results including the optics.
Context: We describe the new SEPIA (Swedish-ESO PI Instrument for APEX) receiver, which was designed and built by the Group for Advanced Receiver Development (GARD), at Onsala Space Observatory (OSO) in collaboration with ESO. It was installed and commissioned at the APEX telescope during 2015 with an ALMA Band 5 receiver channel and updated with a new frequency channel (ALMA Band 9) in February 2016. Aims: This manuscript aims to provide, for observers who use the SEPIA receiver, a reference in terms of the hardware description, optics and performance as well as the commissioning results. Methods: Out of three available receiver cartridge positions in SEPIA, the two current frequency channels, corresponding to ALMA Band 5, the RF band 158--211 GHz, and Band 9, the RF band 600--722 GHz, provide state-of-the-art dual polarization receivers. The Band 5 frequency channel uses 2SB SIS mixers with an average SSB noise temperature around 45K with IF (intermediate frequency) band 4--8 GHz for each sideband providing total 4x4 GHz IF band. The Band 9 frequency channel uses DSB SIS mixers with a noise temperature of 75--125K with IF band 4--12 GHz for each polarization. Results: Both current SEPIA receiver channels are available to all APEX observers.
The prototype of a Davies-Cotton small size telescope (SST-1M) has been designed and developed by a consortium of Polish and Swiss institutions and proposed for the Cherenkov Telescope Array (CTA) observatory. The main purpose of the optical system is to focus the Cherenkov light emitted by extensive air showers in the atmosphere onto the focal plane detectors. The main component of the system is a dish consisting of 18 hexagonal mirrors with a total effective collection area of 6.47 m2 (including the shadowing and estimated mirror reflectivity). Such a solution was chosen taking into account the analysis of the Cherenkov light propagation and based on optical simulations. The proper curvature and stability of the dish is ensured by the mirror alignment system and the isostatic interface to the telescope structure. Here we present the design of the optical subsystem together with the performance measurements of its components.
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$^{primeprime}$ 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 based on a waveguide technique, and the receiver has four intermediate frequency bands of 4.0--8.0 GHz. Over the radio frequency range of 80--116 GHz, the single-sideband receiver noise temperature is lower than about 50 K, and the image rejection ratios are greater than 10 dB in most of the same frequency range. The new receiver system has been installed in the telescope, and we successfully observed a $^{12}$CO ({it J}=3--2) emission line toward a cloverleaf quasar at {it z} = 2.56, which validates the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, is typically 150--300 K at a radio frequency of 97 GHz. We have begun blind search of high-{it J} CO toward high-{it z} submillimeter galaxies.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
