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-Coud´e 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 4 m with a convex hyperboloid surface, the position of which is computer-controlled to follow the moving focal point because the main reflector deforms as the elevation angle changes. The slewing speed of the telescope is 20◦/min (i.e., 0.3◦/sec). The (EL, AZ) driving ranges are also summarized in Table 2. More details on the NRO45 can be found in the Nobeyama Radio Observatory official website [2].

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.