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- Title
Z45: A new 45-GHz band dual-polarization HEMT receiver for the NRO 45-m radio telescope.
- Authors
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 KUNO
- Abstract
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 (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) band 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.
- Subjects
MODULATION-doped field-effect transistors; RADIO telescopes; POLARIZATION (Nuclear physics); INTERMEDIATE frequency amplifiers; MAGNETIC fields; ZEEMAN effect
- Publication
Publications of the Astronomical Society of Japan, 2015, Vol 67, Issue 6, p1
- ISSN
0004-6264
- Publication type
Article
- DOI
10.1093/pasj/psv088