Development of the Phase-up Technology of the Radio Telescopes: 6.7 GHz Methanol Maser Observations with Phased Hitachi 32 m and Takahagi 32 m Radio Telescopes

Kazuhiro Takefuji; Koichiro Sugiyama; Yoshinori Yonekura; Tagiru Saito; Kenta Fujisawa; Tetsuro Kondo

doi:10.1088/1538-3873/aa898c

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arXiv · 1708.09847

Development of the Phase-up Technology of the Radio Telescopes: 6.7 GHz Methanol Maser Observations with Phased Hitachi 32 m and Takahagi 32 m Radio Telescopes

Kazuhiro Takefuji·Koichiro Sugiyama·Yoshinori Yonekura·Tagiru Saito·Kenta Fujisawa·Tetsuro Kondo

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Abstract

For the sake of high-sensitivity 6.7 GHz methanol maser observations, we developed a new technology for coherently combining the two signals from the Hitachi 32 m radio telescope and the Takahagi 32 m radio telescope of the Japanese Very long baseline interferometer Network (JVN), where the two telescopes were separated by about 260 m. After the two telescopes were phased as a twofold larger single telescope, the mean signal-to-noise ratio (SNR) of the 6.7 GHz methanol masers observed by the phased telescopes was improved to 1.254-fold higher than that of the single dish, through a Very Long Baseline Interferometry (VLBI) experiment on the 50 km baseline of the Kashima 34 m telescope and the 1000 km baseline of the Yamaguchi 32 m telescope. Furthermore, we compared the SNRs of the 6.7 GHz maser spectra for two methods. One is a VLBI method and the other is the newly developed digital position switching, which is a similar technology to that used in noise-cancelling headphones. Finally, we confirmed that the mean SNR of method of the digital position switching (ON-OFF) was 1.597-fold higher than that of the VLBI method.

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Kazuhiro Takefuji, Koichiro Sugiyama, Yoshinori Yonekura, Tagiru Saito, Kenta Fujisawa, Tetsuro Kondo. 2017-08-31. Development of the Phase-up Technology of the Radio Telescopes: 6.7 GHz Methanol Maser Observations with Phased Hitachi 32 m and Takahagi 32 m Radio Telescopes. https://doi.org/10.1088/1538-3873%2Faa898c

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