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http://dx.doi.org/10.5303/JKAS.2015.48.2.125

A NEW HARDWARE CORRELATOR IN KOREA: PERFORMANCE EVALUATION USING KVN OBSERVATIONS  

Lee, Sang-Sung (Korea Astronomy and Space Science Institute)
Oh, Chung Sik (Korea Astronomy and Space Science Institute)
Roh, Duk-Gyoo (Korea Astronomy and Space Science Institute)
Oh, Se-Jin (Korea Astronomy and Space Science Institute)
Kim, Jongsoo (Korea Astronomy and Space Science Institute)
Yeom, Jae-Hwan (Korea Astronomy and Space Science Institute)
Kim, Hyo Ryoung (Korea Astronomy and Space Science Institute)
Jung, Dong-Gyu (Korea Astronomy and Space Science Institute)
Byun, Do-Young (Korea Astronomy and Space Science Institute)
Jung, Taehyun (Korea Astronomy and Space Science Institute)
Kawaguchi, Noriyuki (Shanghai Observatory, Chinese Academy of Sciences)
Shibata, Katsunori M. (Mizusawa VLBI Observatory, National Astronomical Observatory of Japan)
Wajima, Kiyoaki (Korea Astronomy and Space Science Institute)
Publication Information
Journal of The Korean Astronomical Society / v.48, no.2, 2015 , pp. 125-137 More about this Journal
Abstract
We report results of the performance evaluation of a new hardware correlator in Korea, the Daejeon correlator, developed by the Korea Astronomy and Space Science Institute (KASI) and the National Astronomical Observatory of Japan (NAOJ). We conduct Very Long Baseline Interferometry (VLBI) observations at 22 GHz with the Korean VLBI Network (KVN) in Korea and the VLBI Exploration of Radio Astrometry (VERA) in Japan, and correlated the aquired data with the Daejeon correlator. For evaluating the performance of the new hardware correlator, we compare the correlation outputs from the Daejeon correlator for KVN observations with those from a software correlator, the Distributed FX (DiFX). We investigate the correlated flux densities and brightness distributions of extragalactic compact radio sources. The comparison of the two correlator outputs shows that they are consistent with each other within < 8%, which is comparable with the amplitude calibration uncertainties of KVN observations at 22 GHz. We also find that the 8% difference in flux density is caused mainly by (a) the difference in the way of fringe phase tracking between the DiFX software correlator and the Daejeon hardware correlator, and (b) an unusual pattern (a double-layer pattern) of the amplitude correlation output from the Daejeon correlator. The visibility amplitude loss by the double-layer pattern is as small as 3%. We conclude that the new hardware correlator produces reasonable correlation outputs for continuum observations, which are consistent with the outputs from the DiFX software correlator.
Keywords
Techniques: interferometric; Instrumentation: interferometers; Radio continuum: galaxies; Masers;
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