Z45: A new 45-GHz b and dual-polarization HEMT receiver for the NRO 45-m radio telescope

Fumitaka Nakamura, Hideo Ogawa, Yoshinori Yonekura, Kimihiko Kimura, Nozomi Okada, Minato Kozu, Yutaka Hasegawa, Kazuki Tokuda, Tetsu Ochiai, Izumi Mizuno, Kazuhito Dobashi, Tomomi Shimoikura, Seiji Kameno, Kotomi Taniguchi, Hiroko Shinnaga, Shuro Takano, Ryohei Kawabe, Taku Nakajima, Daisuke Iono, Nario KunoToshikazu Onishi, Munetake Momose, Satoshi Yamamoto

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

We developed a dual-linear-polarization HEMT (High Electron Mobility Transistor) amplifier receiver system of the 45-GHz b and (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 (JN = 43-32) toward pre-protostellar cores. A linear-polarization receiver system has a smaller contribution of instrumental polarization components to the Stokes V spectra than that of the circular polarization system, so that it is easier to obtain the Stokes V spectra. The receiver has an RF frequency of 42-46 GHz and an intermediate frequency (IF) b and of 4-8 GHz. The typical noise temperature is about 50 K, and the system noise temperature ranges from 100 to 150 K over the frequency of 42-46 GHz. The receiver system is connected to two spectrometers, SAM45 and PolariS. SAM45 is a highly flexible FX-type digital spectrometer with a finest frequency resolution of 3.81 kHz. PolariS is a newly developed digital spectrometer with a finest frequency resolution of 60 Hz, and which has a capability to process the full-Stokes spectroscopy. The half-power beam width (HPBW) was measured to be 37 at 43 GHz. The main beam efficiency of the Gaussian main beam was derived to be 0.72 at 43 GHz. The SiO maser observations show that the beam pattern is reasonably round at about 10% of the peak intensity and the side-lobe level was less than 3% of the peak intensity. Finally, we present some examples of astronomical observations using Z45.

Original languageEnglish
Article number117
JournalPublications of the Astronomical Society of Japan
Volume67
Issue number6
DOIs
Publication statusPublished - Jan 30 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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