Korean VLBI Network (KVN)



2014 Seminar:


08/08/2014   08/29/2014   09/19/2014   09/26/2014   10/24/2014   11/07/2014   11/21/2014   11/28/2014   12/05/2014  

Date
10/24/2014
Speaker
Ms. Jeong Ae Lee (KVN group)
Venue
KASI
Title
Statistical analysis of Anomalous Refraction on KVN sites
Abstract

The fluctuation of VLBI visibility phase can be occurred, predominantly caused by the irregular distribution and motion of water vapor in the atmosphere at high frequencies (>1GHz). This radio-seeing effect shows up on filled-aperture telescopes as an anomalous refraction (AR).

This can be shown as if the antenna pointing-offset increases, in other words the apparent displacement of radio sources from its nominal position happens.

We carried out the single-dish observations on KVN sites in order to check the effect of AR from 2010 to 2014. Orion KL, U Her, and R Leo were observed with 1second sampling time at 22.235GHz and 43.122GHz simultaneously. Each source was observed with the tracking mode for 30 minutes per a source.

We analyzed the structure function, power spectrum and Allan variance of the data according to a day and a night, a season and observatories.

Finally, we can infer that the AR effect depends on the atmospheric environment, especially tropospheric turbulence.


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Korean VLBI Network (KVN)