The Bulletin of The Korean Astronomical Society (천문학회보)
- Volume 42 Issue 1
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- Pages.46.2-46.2
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- 2017
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- 1226-2692(pISSN)
The Power of Simultaneous Multi-frequency Observations for mm-VLBI: Beyond Frequency Phase Transfer
- Zhao, Guang-Yao (UST) ;
- Algaba, Juan Carlos (KASI) ;
- Lee, Sang Sung (KASI) ;
- Jung, Taehyun (KASI) ;
- Dodson, Richard (ICRAR) ;
- Rioja, Maria (ICRAR) ;
- Byun, Do-Young (KASI) ;
- Hodgson, Jeffrey (KASI) ;
- Kang, Sincheol (KASI) ;
- Kim, Dae-Won (SNU) ;
- Kim, Jae-Young (MPIfR) ;
- Kim, Jeong-Sook (NAOJ) ;
- Kim, Soon-Wook (KASI) ;
- Kino, Motoki (KASI) ;
- Miyazaki, Atsushi (KASI) ;
- Park, Jong-Ho (SNU) ;
- Trippe, Sascha (SNU) ;
- Wajima, Kiyoaki (KASI)
- Published : 2017.04.10
Abstract
Atmospheric propagation effects at millimeter wavelengths can significantly alter the phases of radio signals and reduce the coherence time, putting tight constraints on high frequency Very Long Baseline Interferometry (VLBI) observations. In previous works it has been shown that non-dispersive (e.g. tropospheric) effects can be calibrated with the frequency phase transfer (FPT) technique. The coherence time can thus be significantly extended. Ionospheric effects, which can still be significant, remain however uncalibrated after FPT, as well as the instrumental effects. In this work, we implement a further phase transfer between two FPT residuals (i.e. so-called FPT2) to calibrate the ionospheric effects based on their frequency dependence. We show that after FPT2, the coherence time at 3 mm can be further extended beyond 8 hours, and the residual phase errors can be sufficiently canceled by applying the calibration of another source, which can have a large angular separation from the target (>
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