Taehyun Jung

KVN SOURCE-FREQUENCY PHASE-REFERENCING OBSERVATION OF 3C 66A AND 3C 66B

In this proceedings, preliminary results of the KVN Source-Frequency Phase-Referencing (SFPR) observation of 3C 66A and 3C 66B are presented. The motivation of this work is to measure the core-shift of these 2 sources and study the temporal evolution of the jet opacity. Two more sources were observed as secondary reference calibrators and each source was observed at 22, 43, and 86 GHz simultaneously. Our preliminary results show that after using the observations at the lower frequency to calibrate those at the higher frequency of the same source, the residual visibility phases for each source at the higher frequencies became more aligned, and the coherence time became much longer; also, the residual phases for dierent sources, within 10 degrees angular separations, follow similar trends. After reference to the nearby calibrator, the SFPRed maps were obtained as well as the astrometric measurements, i.e. the combined coreshift. The measurements were found to be aected by structural blending eects because of the large beamsize of KVN, but this can be corrected with higher resolution maps (e.g. KAVA maps).

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

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

KVN PHASE REFERENCING OBSERVATIONS OF THE VIRGO CLUSTER

-32.^\circ5

MASK: Multi-frequency AGN Survey with the KVN

in declination. Five hundred thirteen sources were detected in the K and Q bands, simultaneously;

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

\sim76\%

SgrA* 22/43GHz KaVA observation and its Amplitude Calibration

of them are flat-spectrum sources (

Calibrator Survey for evolved stars using the KVN

-0.5 \leq \alpha \leq 0.5

남북한 천문분야 활성화 및 협력 방안 연구

). From the flux--flux relationship, we anticipated that the most of the radiation of many of the sources comes from the compact components. Therefore, the sources listed in the KVNCS are strong candidates for high frequency VLBI calibrators.

The milli-arcsecond scale radio properties of central AGNs in cool-core and non cool-core clusters

By probing nuclear regions and the overall properties of AGN hosts as a function of their environments, we aim to observationally examine how AGN activities are related to their surroundings. We have selected a representative sample of AGN hosts in the Virgo cluster. The selected galaxies are located in a range of density regions showing various morphologies in 1.4 GHz continuum emission. High-resolution observations with the Korean VLBI Network (KVN) allow us to access the inner region of the AGN without suffering from dust extinction and synchrotron self-absorption. Since a number of our targets are too weak to be detected at K-band (22 GHz) within their coherence time, we applied phase referencing to calibrate fast atmospheric phase fluctuations.