AMPLITUDE CORRECTION FACTORS OF KOREAN VLBI NETWORK OBSERVATIONS

IF 1.1 4区物理与天体物理 Q3 ASTRONOMY & ASTROPHYSICS

Journal of the Korean Astronomical Society Pub Date : 2015-07-13 DOI:10.5303/JKAS.2015.48.5.229

Sang-Sung Lee, D. Byun, C. Oh, H. Kim, Jongsoo Kim, T. Jung, Se-jin Oh, D. Roh, Dong-Kyu Jung, J. Yeom

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引用次数: 19

Abstract

We report results of investigation of amplitude calibration for very long baseline interferome-try (VLBI) observations with Korean VLBI Network (KVN). Amplitude correction factors are estimated based on comparison of KVN observations at 22 GHz correlated by Daejeon hardware correlator and DiFX software correlator in Korea Astronomy and Space Science Institute (KASI) with Very Long Base-line Array (VLBA) observations at 22 GHz by DiFX software correlator in National Radio Astronomy Observatory (NRAO). We used the observations for compact radio sources, 3C 454.3, NRAO 512, OJ 287, BL Lac, 3C 279, 1633+382, and 1510−089, which are almost unresolved for baselines in a range of 350-477 km. Visibility data of the sources obtained with similar baselines at KVN and VLBA are se-lected, fringe-fitted, calibrated, and compared for their amplitudes. We find that visibility amplitudes of KVN observations should be corrected by factors of 1.10 and 1.35 when correlated by DiFX and Daejeon correlators, respectively. These correction factors are attributed to the combination of two steps of 2-bit quantization in KVN observing systems and characteristics of Daejeon correlator.

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韩国vlbi网观测的幅值校正因子

本文报道了利用韩国VLBI网络(KVN)对甚长基线干涉仪(VLBI)观测进行幅度校准的研究结果。利用韩国天文空间科学研究所(KASI)大田硬件相关器和DiFX软件相关器相关的22 GHz KVN观测数据与国家射电天文台(NRAO) DiFX软件相关器相关的22 GHz甚长基线阵列(VLBA)观测数据进行对比，估算了振幅校正因子。我们使用了紧凑射电源的观测数据，3C 454.3、NRAO 512、OJ 287、BL Lac、3C 279、1633+382和1510−089，在350-477 km的基线范围内几乎无法解决。在KVN和VLBA获得的具有相似基线的源的能见度数据经过选择、条纹拟合、校准并比较其幅度。利用DiFX和大田相关器进行相关时，KVN观测值的能见度振幅应分别以1.10和1.35因子进行校正。这些校正因子是由于KVN观测系统中2位量化两步的结合和大田相关器的特性所致。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of the Korean Astronomical Society 地学天文-天文与天体物理

CiteScore

1.30

自引率

10.00%

发文量

审稿时长

>12 weeks

期刊介绍： JKAS is an international scientific journal publishing papers in all fields of astronomy and astrophysics. All manuscripts are subject to the scrutiny of referees. Manuscripts submitted to JKAS must comply with the ethics policy of JKAS. Six regular issues are published each year on February 28, April 30, June 30, August 31, October 31, and December 31. One year''s issues compose one volume.