KVN and VERA Array (KaVA)


KaVA consists of 7 antenna sites in VERA-Mizusawa, VERA-Iriki, VERA-Ogasawara, VERA-Ishigakijima, KVN-Yonsei, KVN-Ulsan and KVN-Tamna with 21 baselines(see Figure 1). The maximum baseline length is 2270 km between Mizusawa and Ishigakijima, and the minimum baseline length is 305 km between Yonsei and Ulsan. The maximum angular resolution expected from the baseline length is about 1.2 mas for K bandand about 0.6 mas for Q band. The geographic locations and coordinate of each KaVA antenna in the coordinate system of epoch 2009.0 are summarized in table 1. figure 2 shows examples of uv plane coverage.

The averaged velocities of VERA sites in Table 2 are predicted value at the epoch of January 01, 2015. Reference frame of these coordinates is ITRF2008. The rates of the coordinates of Mizusawa, Iriki, Ogasawara and Ishigakijima are the average value of change of the coordinates from January 01, 2014 to December 31, 2014. The 2011 off the Pacific coast of Tohoku Earthquake (Mj=9.0) brought the co-seismic large step and non-linear post-seismic movement to the coordinates of Mizusawa. Co-seismic steps of the coordinates of Mizusawa are dX=-2.0297m, dY=-1.4111m and dZ=-1.0758m. The creeping continues still now, though decreased.

Figure 2: The uv plane coverage (±3000km) expected with KaVA antennas from an observation over elevation of 20. Each panel shows the uv coverage for the declination of 60o (left), 20o (center), and -20o (right).

The changes of coordinates by the post-seismic creeping are dX=-0.8574m, dY=-0.5387m and dZ=-0.2398m in total from March, 12, 2011 to Jan, 01, 2015.

In the case of KVN, all antenna locations are measured with GPS system. The antenna positions of KVN are regularly monitored both with GPS system and geodetic VLBI observations in collaboration with VERA. No velocity information is available for KVN stations.

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KaVA ( KVN and VERA Array )