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The Korean Astronomical Society (한국천문학회)
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A STUDY ON THE RELIABILITY OF THE DAEJEON HARDWARE CORRELATOR FOR THE KVN OBSERVATION MODES

KVN 관측모드별 대전상관기의 상관결과 고찰

  • Received : 2015.11.09
  • Accepted : 2016.07.07
  • Published : 2016.09.30
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Abstract

This paper presents the results of test observations toward a point source, 4C39.25, for observation modes with various bandwidths and numbers of IF streams in order to examine a reliability of the Daejeon hardware correlator performance for correlating VLBI (Very Long Baseline Interferometry) data obtained with the several observation modes of the KVN (Korean VLBI Network). We used a DiFX software correlator (DiFX) as a reference, for investigating the output visibilities from the Daejeon corelator. It is found that the band shapes of the output visibilities from two correlators are similar to each other and the correlated flux density for each baseline obtained from the Daejeon hardware correlator is lower by 3 - 7% than that from the DiFX. The flux difference is attributed to the limitation of FPGA resources and the difference of fringe rotation algorithm of the Daejeon hardware correlator. The conversion factor, 0.93 ~ 0.97, is proposed for future correlation with the Daejeon hardware correlator.

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References

  1. Deller, A. T., Brisken, W. F., Phillips, C. J., et al., 2011, DiFX-2: A More Flexible, Efficient, Robust, and Powerful Software Correlator, PASP 123, 275 https://doi.org/10.1086/658907
  2. Lee S. -S., Oh C. -S., Roh D. -G., et al. 2015a, A New Hardware Correlator in Korea: Performance Evaluation Using KVN Observations, JKAS, 48, 125
  3. Lee S. -S., Byun D. -Y., Oh C. -S., et al. 2015b, Amplitude Correction Factors of Korean VLBI Network Observations, JKAS, 48, 229
  4. Oh, S. -J., Roh, D. -G., Yeom, J. -H., et al., 2009, A Study on Development of VLBI Correlation Trial Product, PKAS 24, 1
  5. Oh, S. -J., Roh, D. -G., Yeom, J. -H., et al., 2011a, Performance Evaluation of VLBI Correlation Subsystem Main Product, JISPS 12, 4, 322
  6. Oh, S. -J., Roh, D. -G., Yeom, J. -H., et al., 2015, A Study on Solving of Double-layer Pattern Problem for Daejeon Correlator, JISPS 16, 4, 162
  7. Oh, S. -J., Roh, D. -G., Wajima K., Kawaguchi N., et al., 2011b, Design and Development of a High-speed Data-Acquisition System for the Korean VLBI Network, PASJ 63, 1229 https://doi.org/10.1093/pasj/63.6.1229
  8. Roh, D. -G., Oh, S. -J., Yeom, J. -H., et al., 2008, 2008 Annual Report on Korea-Japan Joint VLBI Correlator and Receiver Development, Korea Astronomy and Space Science Institute
  9. Takahashi, F., Kondo, T., & Koyama, Y., 2000, Very Long Baseline Interferometer, Ohmsha
  10. Oyama T., et al., 2008, The Development and Performance of a New 4 Gbps Disk Recorder and eVLBI Systems Using a 10 GbE Network, 2008 General Meeting of IVS.
  11. Shepherd, M. C., 1997, in Astronomical Data Analysis Software and Systems VI, eds. Gareth Hunt & H. E. Payne, ASP Conf. Ser., 125