KVN and VERA Array

Brief Summary of VERA Antennas

All the telescopes of VERA have the same design, being a Cassegrain-type antenna on AZ-EL mount. Each telescope has a 20 m diameter dish with a focal length of 6 m, with a sub-reflector of 2.6 m diameter. The dual-beam receiver systems are installed at the Cassegrain focus. Two receivers are set up on the Stewart-mount platforms, which are sustained by steerable six arms, and with such systems one can simultaneously observe two adjacent objects with a separation angle between 0.32 and 2.2 deg.

The whole receiver systems are set up on the field rotator (FR), and the FR rotate to track the apparent motion of objects due to the earth rotation. Table 3 summarizes the ranges of elevation (EL), azimuth (AZ) and field rotator angle (FR) with their driving speeds and accelerations. In the case of single beam observing mode, one of two beams is placed at the antenna vertex (separation offset of 0 deg).

Table 3:Driving performance of KaVA antennas.
Driving axis Driving range Max. driving speed Max. driving acceleration
VERA
AZ 90450 2.1/sec 2.1/sec$^2$
EL 585 2.1/sec 2.1/sec$^2$
FR 270270 3.1/sec 3.1/sec$^2$
KVN
AZ 90450 3/sec 3/sec$^2$
EL 585 3/sec 3/sec$^2$
The north is 0 and the east is 90.
FR is 0 when Beam-1 is at the sky side and Beam-2 is at the ground side,
 and CW is positive when an antenna is seen from a target source.

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KaVA ( KVN and VERA Array )