Millimeter-wave Receiver Optics for Korean VLBI Network

Han, Seog-Tae; Lee, Jung Won; Kang, Jin Wook; Je, Do‐Heung; Chung, Moon Hyun; Wi, Seog-Oh; Sasao, Tetsuo; Wylde, Richard

doi:10.1007/s10762-007-9296-7

Cited by 62 publications

(48 citation statements)

References 5 publications

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“…The antennas are equipped with the quasi-optic system that allows simultaneous observations at 22, 43, 86, and 129 GHz. This system is described in detail in Han et al (2008).…”

Section: Introduction the Korean Vlbi Network (Kvn) Is The First Dedimentioning

confidence: 99%

EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: THE QCAL-1 43 GHz CALIBRATOR SURVEY

Petrov¹,

Lee

Kim

et al. 2012

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This paper presents the catalog of correlated flux densities in three ranges of baseline projection lengths of 637 sources from a 43 GHz (Q-band) survey observed with the Korean VLBI Network. Of them, 14 objects used as calibrators were previously observed, but 623 sources have not been observed before at Q−band with very long baseline interferometry (VLBI). The goal of this work in the early science phase of the new VLBI array is twofold: to evaluate the performance of the new instrument that operates in a frequency range of 22-129 GHz and to build a list of objects that can be used as targets and as calibrators. We have observed the list of 799 target sources with declinations down to −40• . Among them, 724 were observed before with VLBI at 22 GHz and had correlated flux densities greater than 200 mJy. The overall detection rate is 78%. The detection limit, defined as the minimum flux density for a source to be detected with 90% probability in a single observation, was in a range of 115-180 mJy depending on declination. However, some sources as weak as 70 mJy have been detected. Of 623 detected sources, 33 objects are detected for the first time in VLBI mode. We determined their coordinates with the median formal uncertainty 20 mas. The results of this work set the basis for future efforts to build the complete flux-limited sample of extragalactic sources at frequencies 22 GHz and higher at 3/4 of the celestial sphere.

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“…The antennas are equipped with the quasi-optic system that allows simultaneous observations at 22, 43, 86, and 129 GHz. This system is described in detail in Han et al (2008).…”

Section: Introduction the Korean Vlbi Network (Kvn) Is The First Dedimentioning

confidence: 99%

EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: THE QCAL-1 43 GHz CALIBRATOR SURVEY

Petrov¹,

Lee

Kim

et al. 2012

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“…Jung et al (2011) demonstrated the excellence of multi-frequency phase referencing on atmospheric phase compensation in mm-VLBI. Based on this advantage, the KVN (Kim et al 2004;Lee et al 2014) as the first dedicated mm-VLBI array, addresses one of the fundamental limitations of the field, the atmospheric stability, by introducing the simultaneous multi-frequency receiver system (Han et al 2008). The KVN currently consists of three antennas spread across South Korea, located in Seoul and Ulsan in the main land, and in Jeju island.…”

Section: Figurementioning

confidence: 99%

Measuring the Core Shift Effect in Agn Jets With the Extended Korean Vlbi Network

Dodson¹,

Han²,

Rioja³

et al. 2015

Journal of The Korean Astronomical Society

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We present our efforts for extending the simultaneous multi-frequency receiver system of the Korean Very Long Baseline Interferometry (VLBI) Network (KVN) to global baselines in order to measure the frequency-dependent position shifts in Active Galactic Nuclei (AGN) jets, the so called core shift effect, with an unprecedented accuracy (a few micro-arcseconds). Millimeter VLBI observations with simultaneous multi-frequency receiver systems, like those of the KVN, enable us to explore the innermost regions of AGN and high precision astrometry. Such a system is capable of locating the frequency dependent opacity changes accurately. We have conducted the feasibility test-observations with the interested partners by implementing the KVN-compatible systems. Here we describe the science case for measuring the core shift effect in the AGN jet and report progress and future plans on extending the simultaneous multi-frequency system to global baselines.

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“…The so-called East Asian VLBI Network (EAVN) is expected to be comparable to VLBA or EVN in spatial resolution, sensitivity, and imaging capability (e.g., Yi & Jung 2008). In addition, KVN will be operated in four (22/43/86/129 GHz) different frequency bands simultaneously using multi-frequency band receiver systems (Han et al 2008). Simultaneous multi-frequency observations will make it possible to use the 22 GHz data for performing phase calibrations of higher-frequency data (Jung et al 2011).…”

Section: Korean Vlbi Network (Kvn)mentioning

confidence: 99%

KVN Single-dish Water and Methanol Maser Line Surveys of Galactic YSOs

Kim¹,

Byun²,

Bae³

et al. 2012

Proc. IAU

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Abstract. We have carried out simultaneous 22 GHz H2 O and 44 GHz Class I CH3 OH maser line surveys of more than 1500 intermediate-and high-mass YSOs in the Galaxy using newlyconstructed KVN 21-m telescopes. As the central (proto)stars evolve, the detection rates of the two masers rapidly decrease for intermediate-mass YSOs while the rates increase for high-mass YSOs. These results suggest that the occurrence of the two masers is closely related both to the evolutionary stage of the central objects and to the circumstellar environments. CH 3 OH masers always have very similar velocities (<10 km s −1 ) to the natal dense cores, whereas H2 O masers often have significantly different velocities. The isotropic luminosities of both masers are well correlated with the bolometric luminosities of the central (proto)stars.

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Millimeter-wave Receiver Optics for Korean VLBI Network

Cited by 62 publications

References 5 publications

EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: THE QCAL-1 43 GHz CALIBRATOR SURVEY

EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: THE QCAL-1 43 GHz CALIBRATOR SURVEY

Measuring the Core Shift Effect in Agn Jets With the Extended Korean Vlbi Network

KVN Single-dish Water and Methanol Maser Line Surveys of Galactic YSOs

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