Obtaining accurate antenna positions are important in VLBI system, especially for high precision astrometry. Mizusawa antenna has been participating in international geodesy observations at S/X frequency bands and all VERA stations are measuring their relative positions by K-band geodetic VLBI observations internally. In order to determine and maintain accurate positions of three KVN antennas, KVN and VERA started the K-band geodesy VLBI program in 2011.
|Obs. Code||Obs. Date||Antenna||Note|
|r11333k||2011 Nov 29||Ky Ku Kt Vm Vr Vs Vo||only VERA+KVN Yonsei solution was obtained|
|r11361k||2011 Dec 27||Ky Kt Vm Vr Vs Vo||observation was failed|
|r12271k||2012 Sep 27||Ky Ku Kt Vm Vr Vs Vo||all solutions were obtained|
|r13088k||2013 Mar 29||Ky Ku Kt Vm Vr Vs Vo||all solutions were obtained|
|r13140k||2013 May 20||Ky Ku Kt Vm Vr Vs Vo||all solutions were obtained|
|r13251k||2013 Sep 08||Ky Ku Kt Vm Vr Vs Vo||in progress|
|r13313k||2013 Nov 09||Ky Ku Kt Vm Vr Vs Vo||in progress|
|r14028k||2014 Jan 28||Ky Ku Kt Vm Vr Vs Vo||in progress|
|r14095k||2014 Apr 05||Ky Ku Kt Vm Vr Vs Vo||in progress|
* Ky, Ku, Kt stand for Yonsei, Ulsan, and Tamna antennas in KVN, respectively.
* Vm, Vr, Vs, Vo represent Mizusawa, Iriki, Ishigaki-jima,and Ogasawara antennas in VERA, respectively.
At present, KVN antenna position was measured by using two dual-band GPS antennas (see the section, "GPS measurement") and has been used for KVN(+VERA) VLBI observations and K-band geodetic VLBI observations. The geodetic VLBI solutions were not applied to KVN antenna positions yet since they are still undergoing testing and confirmation.
The accuracy of GPS measurement is approximately about 5 cm and the typical 1-sigma errors of geodetic solutions analyzed by Dr. Jike (Mizusawa observatory, VERA) are about 0.4 cm in X, Y, and Z directions for one successful measurement.
We are regularly monitoring KVN antenna positions using GPS and geodetic VLBI observations.
The first KVN K-band geodesy VLBI was performed on Feb. 1, 2012. Total 85 ICRF sources were observed with 1 Gbps (256MHz bandwidth) data rate. The correlation has been done with DiFX software correlator and the data analysis is in progress.