AMPLITUDE CORRECTION FACTORS OF KOREAN VLBI NETWORK OBSERVATIONS
AMPLITUDE CORRECTION FACTORS OF KOREAN VLBI NETWORK OBSERVATIONS
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韩国VLBI网络观测的幅度校正因子
DOI：
10.5303/jkas.2015.48.5.229
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发表时间：
2015
影响因子：
1
通讯作者：
J. Yeom
中科院分区：
文献类型：
--
作者：
Sang;D. Byun;C. Oh;H. Kim;Jongsoo Kim;T. Jung;Se;D. Roh;Dong;J. Yeom
本文报道了韩国VLBI观测网（KVN）甚长基线干涉测量（VLBI）振幅定标的研究结果。根据韩国天文和空间科学研究所（KASI）的大田硬件相关器和DiFX软件相关器在22 GHz的KVN观测值与国家射电天文台（NRAO）的DiFX软件相关器在22 GHz的甚长基线阵列（VLBA）观测值的比较，估计了振幅校正因子。我们使用了致密射电源3C 454.3、NRAO 512、OJ 287、BL Lac、3C 279、1633+382和1510−089的观测结果，这些射电源在350-477 km的基线范围内几乎无法分辨。对在KVN和VLBA处使用相似基线获得的源的可见性数据进行选择、边缘拟合、校准并比较其振幅。我们发现，KVN观测的可见度振幅应分别由1.10和1.35的因子进行校正，当与DiFX和大田修正因子相关时。这些校正因子是由于KVN观测系统中两步2比特量化和大田相关器的特性相结合而产生的。
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.