East Asian VLBI Network (EAVN)

Brief Summary of VERA Antennas

The Nobeyama 45-m Telescope (hereafter NRO45) is one of the largest millimeter radio telescope in the world. It has a Cassegrain-Coudé optics. The paraboloidal main reflector consists of about 600 pieces of panels, each of which has a surface accuracy of about 60 microns, and the deviation of the whole antenna from an ideal paraboloid is about 90 microns. The sub-reflector has a diameter of 4m with a convex hyperboloid surface, the position of which is computer-controlled to follow the moving focal point because the main re ector deforms as the elevation angle changes. The slewing speed of the antenna is 20◦/min (i.e., 0.3◦/sec). The (EL, AZ) driving ranges are also summarized in Table 2. More details on the NRO45 antenna can be found in the official NRO website [2].

Table 1: Geographic locations of each EAVN antenna.
Site East
Longitude
[◦ ′ ′′]
North
Latitude
[◦ ′ ′′]
Ellipsoidal
Height
[m]
X
[m]
Y
[m]
Z
[m]
Nobeyamaa 138 28 21.2 35 56 40.9 1350 -3871025.4987 3428107.3984 3724038.7361
Tianmab 121 08 09.4 30 55 19.8 49.2 -2826708.6380 4679237.0440 3274667.5330
Mizusawac 141 07 57.3 39 08 00.7 116.4 -3857244.6475 3108782.9982 4003899.2132
Irikic 130 26 23.6 31 44 52.4 573.6 -3521719.8292 4132174.6212 3336994.1399
Ogasawarac 142 12 59.8- 27 05 30.5 273.1 -4491068.5584 3481545.0777 2887399.7419
Ishigakijimac 124 10 15.6 24 24 43.8 65.1 -3263995.1630 4808056.3180 2619948.7989
Yonseid 126 56 27.4 37 33 54.9 139 -3042280.9137 4045902.7164 3867374.3544
Ulsand 129 14 59.3 35 32 44.2 170 -3287268.6186 4023450.1799 3687380.0198
Tamnad 126 27 34.4 33 17 20.9 452 -3171731.5580 4292678.4878 3481038.7252
aThe position was measured in late 2016.
bbThe epoch of the coordinate is January 01, 2014.
cThe epoch of the coordinates is January, 01, 2015.
dThe antenna positions are obtained by the KaVA K-band geodesy program on January 24, 2014.

The aperture efficiency and beam size of the NRO45 at K- and Q-bands are listed in Table 3. The values for NRO45 are based on the latest measurements in autumn 2017, where the Jupiter or the Mars was used as a reference source. The elevation dependence of the aperture efficiency is approximately constant over a range of El ~ 25◦ -50◦ at both K- and Q-bands.




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EAVN ( East Asia VLBI Network)