Do-Young Byun

INTERFEROMETRIC MONITORING OF GAMMA-RAY BRIGHT AGNs. I. THE RESULTS OF SINGLE-EPOCH MULTIFREQUENCY OBSERVATIONS

We present results of single-epoch very long baseline interferometry (VLBI) observations of gamma-ray bright active galactic nuclei (AGNs) using the Korean VLBI Network (KVN) at 22, 43, 86, and 129~GHz bands, which are part of a KVN key science program, Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA). We selected a total of 34 radio-loud AGNs of which 30 sources are gamma-ray bright AGNs with flux densities of

First simultaneous 4-frequency phase referencing test for mm-VLBI observation

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Korean VLBI Network Calibrator Survey (KVNCS). 1. Source Catalog of KVN Single-dish Flux Density Measurement in the K and Q Bands

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Korean VLBI Network receiver optics for simultaneous multi-frequency observation

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Mm-VLBI Phase correction capability with the korean VLBI Network

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Understanding high-mass star formation through KaVA observations of water and methanol masers

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Linear polarisation of Class I methanol masers in massive star formation regions

. Single-epoch multi-frequency VLBI observations of the target sources were conducted during a 24-hr session on 2013 November 19 and 20. All observed sources were detected and imaged at all frequency bands with or without a frequency phase transfer technique which enabled the imaging of 12 faint sources at 129~GHz, except for one source. Many of the target sources are resolved on milliarcsecond scales, yielding a core-jet structure with the VLBI core dominating the synchrotron emission on the milliarcsecond scale. CLEAN flux densities of the target sources are 0.43-28~Jy, 0.32-21~Jy, 0.18-11~Jy, and 0.35-8.0~Jy in the 22, 43, 86, and 129~GHz bands, respectively.

MASK: Multi-frequency AGN Survey with the KVN

We present the results of the first 4-frequency simultaneous VLBI fringe detection at 22, 43, 86, and 129 GHz with the Korean VLBI Network (KVN) along with a multi-frequency phase referencing (MFPR) test. The KVN employed a new multi-frequency receiver system that can observe four different radio bands (22/43/86/129 GHz) simultaneously. This system is expected to be an excellent tool to calibrate the atmospheric phase fluctuations by applying MFPR. 4-frequency simultaneous fringes of 3C279 at 22, 43, 86, and 129 GHz were first successfully detected on all three KVN baselines in April 2012. The tight correlation of fringe phases between the four frequencies is a clear indication of a non-dispersive characteristic of the neutral troposphere to the radio systems. A high signal-to-noise ratio fringe-detection of 3C279 at 129 GHz was obtained by referencing to the 22 GHz fringes. This initial experiment demonstrates the feasibility of MFPR as an effective way to overcome short coherence time in mm-VLBI.

Detection of short-term flux variability and intraday variability in polarized emission at millimeter-wavelength from S5 0716+714

We present the catalog of the KVN Calibrator Survey (KVNCS). This first part of the KVNCS is a single dish radio survey conducted at 22 (K band) and 43 GHz (Q band) simultaneously using the Korean VLBI Network (KVN) from 2009 to 2011. A total 2045 sources selected from the VLBA Calibrator Survey (VCS) with an extrapolated flux density limit of 100 mJy at K band. The KVNCS contains 1533 sources in the K band with a flux density limit of 70 mJy and 553 sources in the Q band with a flux density limit of 120 mJy; it covers the whole sky down to

KOREAN VLBI NETWORK CALIBRATOR SURVEY (KVNCS): 1. SINGLE DISH FLUX MEASUREMENT IN THE K AND Q BANDS

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