• Zhao, Guang-Yao (Korea Astronomy and Space Science Institute) ;
  • Jung, Taehyun (Korea Astronomy and Space Science Institute) ;
  • Sohn, Bong Won (Korea Astronomy and Space Science Institute) ;
  • Kino, Motoki (Kogakuin University, Academic Support Center) ;
  • Honma, Mareki (National Astronomical Observatory of Japan) ;
  • Dodson, Richard (ICRAR, M468, University of Western Australia) ;
  • Rioja, Maria (ICRAR, M468, University of Western Australia) ;
  • Han, Seog-Tae (Korea Astronomy and Space Science Institute) ;
  • Shibata, Katsunori (National Astronomical Observatory of Japan) ;
  • Byun, Do-Young (Korea Astronomy and Space Science Institute) ;
  • Akiyama, Kazunori (Massachusetts Institute of Technology, Haystack Observatory) ;
  • Algaba, Juan-Carlos (Department of Physics and Astronomy, Seoul National University) ;
  • An, Tao (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Cheng, Xiaopeng (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Cho, Ilje (Korea Astronomy and Space Science Institute) ;
  • Cui, Yuzhu (National Astronomical Observatory of Japan) ;
  • Hada, Kazuhiro (National Astronomical Observatory of Japan) ;
  • Hodgson, Jeffrey A. (Korea Astronomy and Space Science Institute) ;
  • Jiang, Wu (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Lee, Jee Won (Korea Astronomy and Space Science Institute) ;
  • Lee, Jeong Ae (Department of Physics and Astronomy, Seoul National University) ;
  • Niinuma, Kotaro (Graduate School of Sciences and Technology for Innovation, Yamaguchi University) ;
  • Park, Jong-Ho (Department of Physics and Astronomy, Seoul National University) ;
  • Ro, Hyunwook (Department of Astronomy, Yonsei University) ;
  • Sawada-Satoh, Satoko (Graduate School of Science and Engineering, Kagoshima University) ;
  • Shen, Zhi-Qiang (Shanghai Astronomical Observatory, Chinese Academy of Sciences) ;
  • Tazaki, Fumie (National Astronomical Observatory of Japan) ;
  • Trippe, Sascha (Department of Physics and Astronomy, Seoul National University) ;
  • Wajima, Kiyoaki (Korea Astronomy and Space Science Institute) ;
  • Zhang, Yingkang (Shanghai Astronomical Observatory, Chinese Academy of Sciences)
  • Received : 2018.08.06
  • Accepted : 2019.01.23
  • Published : 2019.02.28


The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implement compatible optics systems. Simultaneous dual/multi-frequency VLBI observations at mm wavelengths with international baselines are thus possible. In this paper, we present the results from the first successful simultaneous 22/43 GHz dual-frequency observation with KaVA(KVN and VERA array), including images and astrometric results. Our analysis shows that the newly implemented simultaneous receiving system has brought a significant extension of the coherence time of the 43 GHz visibility phases along the international baselines. The astrometric results obtained with KaVA are consistent with those obtained with the independent analysis of the KVN data. Our results thus confirm the good performance of the simultaneous receiving systems for the nonKVN stations. Future simultaneous observations with more global stations bring even higher sensitivity and micro-arcsecond level astrometric measurements of the targets.

CMHHBA_2019_v52n1_23_f0001.tif 이미지

Figure 1. Self-calibrated images of 4C 39.25 (left) and 0945+408 (right) at 22 (upper) and 43 GHz (lower). The beams are shown in the lower left corner. The contour levels start from 3 times the r.m.s level and increase by a factor of 2.

CMHHBA_2019_v52n1_23_f0002.tif 이미지

Figure 2. visibility phases of 4C 39.25 along MIZ baselines at 43 GHz before (dots) and after (crosses) applying FPT from 22 GHz; Each point on the plot corresponds to a temporal average of 10 seconds.

CMHHBA_2019_v52n1_23_f0003.tif 이미지

Figure 3. Fractional flux recovery as functions of solution intervals for phase self-calibration, for the visibility phases before (dot-dashed line) and after (dashed line) applying FPT. The coherence time corresponds to a fractional flux recovery of 0.6.

CMHHBA_2019_v52n1_23_f0004.tif 이미지

Figure 4. SFPRed visibility phases of 0945+408 on all baselines at 43 GHz with a temporal average of 60s. The numbers in the parentheses in each panel correspond to the station codes of each antenna used by the correlator.

CMHHBA_2019_v52n1_23_f0005.tif 이미지

Figure 5. KaVA SFPRed map of 0945+408 at 43 GHz. The beam is 1.28 × 0.70 mas with a position angle of −71°. The grid serves as a visual guide for the offset of the peak of brightness from the center of the map.

CMHHBA_2019_v52n1_23_f0006.tif 이미지

Figure 6. Comparison of astrometric results from the SFPR analysis on the KaVA (squares) and KVN (circles) data with point source models (open symbols), structural models in Section 3.1 (half-filled symbols), and structual models from Niinuma et al. 2014 for 4C 39.25 (filled symbols).


Supported by : National Research Foundation of Korea (NRF)


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