KVNCS: 2. The Fringe Survey of New Candidates for VLBI Calibrators in the K Band

• Published in: Journal of the Korean Astronomical Society, 56(2) Vol. 56; no. 2; pp. 159 - 168
• Main Authors: Jeong Ae Lee, Taehyun Jung, Bong Won Sohn, Do-Young Byun
• Format: Journal Article
• Language: English
• Published: 한국천문학회 01.07.2023
• Subjects: 천문학; surveys; quasars: general; catalogues; galaxies: active; astrometry; radio continuum: galaxies
• ISSN: 1225-4614; 2288-890X
• DOI: 10.5303/JKAS.2023.56.2.159

The main goal of the Korean VLBI Network Calibrator Survey (KVNCS) is to expand the VLBI calibrators catalog for KVN, KaVA(KVN and VERA Array), EAVN(East-Asian VLBINetwork), and other extended regions. The secondKVNCS (KVNCS2) aimed to detect VLBI fringes of new candidates for calibrators in the K band. Out of the 1533 sources whose single-dish flux density in the K band was measured with KVN telescopes (Lee et al. 2017), 556 sources were observed with KVN in the K band. KVNCS2 confirmed the detection of VLBI fringes of 424 calibrator candidates over a single baseline. All detected sources had a high Signal-to-Noise Ratio (SNR) of >25. Finally, KVNCS2 confirmed 347 new candidates as VLBI calibrators in the K band, resulting in a 5% increase in the sky coverage compared to previous studies. The spatial distribution was quasi-uniform across the observable region (Dec. > −32.5◦). In addition, the possibility as calibrator candidates for the detected sources was checked, using an analysis of the flux-flux relationship. Ultimately, the KVNCS catalog will not only become the VLBI calibrator list but is also useful as a database of compact radio sources for astronomical studies.