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A new off-point-less observing method for millimeter and submillimeter spectroscopy with a frequency-modulating local oscillator
http://hdl.handle.net/2237/00032697
http://hdl.handle.net/2237/00032697665616d3-060b-4277-b706-b3c3bff3c1ba
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
main-90f82d3 (7.1 MB)
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| Item type | 学術雑誌論文 / Journal Article(1) | |||||
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| 公開日 | 2020-10-05 | |||||
| タイトル | ||||||
| タイトル | A new off-point-less observing method for millimeter and submillimeter spectroscopy with a frequency-modulating local oscillator | |||||
| 言語 | en | |||||
| 著者 |
Taniguchi, Akio
× Taniguchi, Akio× Tamura, Yoichi× Kohno, Kotaro× Takahashi, Shigeru× Horigome, Osamu× Maekawa, Jun× Sakai, Takeshi× Kuno, Nario× Minamidani, Tetsuhiro |
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| アクセス権 | ||||||
| アクセス権 | open access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||
| 権利 | ||||||
| 言語 | en | |||||
| 権利情報 | This is a pre-copyedited, author-produced version of an article accepted for publication in [Publications of the Astronomical Society of Japan] following peer review. The version of record [Publications of the Astronomical Society of Japan. v.72, n.1, 2020, p.2] is available online at: http://doi.org/10.1093/pasj/psz121. | |||||
| キーワード | ||||||
| 主題Scheme | Other | |||||
| 主題 | atmospheric effects | |||||
| キーワード | ||||||
| 主題Scheme | Other | |||||
| 主題 | methods: data analysis | |||||
| キーワード | ||||||
| 主題Scheme | Other | |||||
| 主題 | methods: observational | |||||
| キーワード | ||||||
| 主題Scheme | Other | |||||
| 主題 | techniques: imaging spectroscopy | |||||
| キーワード | ||||||
| 主題Scheme | Other | |||||
| 主題 | techniques: spectroscopic | |||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | We propose a new observing method for single-dish millimeter and submillimeter spectroscopy using a heterodyne receiver equipped with a frequency-modulating local oscillator (FMLO). Unlike conventional switching methods, which extract astronomical signals by subtracting the reference spectra of off-sources from those of on-sources, the FMLO method does not need to obtain any off-source spectra; rather, it estimates them from the on-source spectra themselves. The principle uses high-dump-rate (10 Hz) spectroscopy with radio frequency modulation achieved by fast sweeping of a local oscillator of a heterodyne receiver. Because sky emission (i.e., off-source) fluctuates as 1/f and is spectrally correlated, it can be estimated and subtracted from time series spectra (a timestream) by principal component analysis. Meanwhile, astronomical signals remain in the timestream since they are modulated to a higher time-frequency domain. The FMLO method therefore achieves (1) a remarkably high observation efficiency, (2) reduced spectral baseline wiggles, and (3) software-based sideband separation. We developed an FMLO system for the Nobeyama 45m telescope and a data reduction procedure for it. Frequency modulation was realized by a tunable and programmable first local oscillator. With observations of Galactic sources, we demonstrate that the observation efficiency of the FMLO method is dramatically improved compared to conventional switching methods. Specifically, we find that the time to achieve the same noise level is reduced by a factor of 3.0 in single-pointed observations and by a factor of 1.2 in mapping observations. The FMLO method can be applied to observations of fainter (∼mK) spectral lines and larger (∼deg^2) mapping. It offers much more efficient and baseline-stable observations compared to conventional switching methods. | |||||
| 言語 | en | |||||
| 内容記述 | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | ファイル公開日: 2021/02/01 | |||||
| 言語 | ja | |||||
| 出版者 | ||||||
| 出版者 | Oxford University Press | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプresource | http://purl.org/coar/resource_type/c_6501 | |||||
| タイプ | journal article | |||||
| 出版タイプ | ||||||
| 出版タイプ | AM | |||||
| 出版タイプResource | http://purl.org/coar/version/c_ab4af688f83e57aa | |||||
| DOI | ||||||
| 関連タイプ | isVersionOf | |||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | https://doi.org/10.1093/pasj/psz121 | |||||
| ISSN（print） | ||||||
| 収録物識別子タイプ | PISSN | |||||
| 収録物識別子 | 0004-6264 | |||||
| 書誌情報 |
en : Publications of the Astronomical Society of Japan 巻 72, 号 1, p. 2, 発行日 2020-02 |
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| 著者版フラグ | ||||||
| 値 | author | |||||
