VLBI Exploration of Radio Astrometry (VERA) is a VLBI facility operated by the National Astronomical Observatory of Japan. It comprises four 20 m radio telescopes located across the country. VLBI observations at 86 GHz allow us to explore the jet base of nearby active galactic nuclei. In recent years, the development of the 86 GHz receiver systems at the East Asia VLBI Network (EAVN) has started. Currently, only three Korea VLBI Network (KVN) antennas provide 86 GHz VLBI capability in the member stations of EAVN. The participation of VERA in the 86 GHz VLBI observations will boost resolution, sensitivity, and dynamic range. Therefore, we are developing a new 86 GHz low noise receiver system to be installed at VERA Mizusawa and Ishigaki stations. We are considering a cooled circular polarization receiver covering a wide frequency range of 67−116 GHz with the capability of cooling HEMT amplifiers. We are developing a room temperature 2 side band (2SB) system for down-converting signals in the 67−116 GHz band. Recently developed room-temperature mixers with an IF frequency over 25 GHz could cover most of the 67−116 GHz RF signals in a single observation. In this poster, we will discuss the development progress of the 2SB receiver and the design status of the cooling Dewar.
The new VLBI data acquisition system (OCTAVE-DAS) have been developed for VLBI Exploration of Radio Astrometry (VERA) and the East Asia VLBI Network (EAVN) based on the VSI-H and VDIF specifications at the National Astronomical Observatory of Japan. It consists of 1) a high speed 1-20 Gsps 3-10 bit RF(-30 GHz) direct sampler with DBBC functions, 2) media converter between one 10 GigE port and four 2 Gbps input and output ports conformable to VSI-H, 3) new VLBI recorders have functions of both recording and playing at a maximum rate of 32 Gbps and 4) Gbit real-time correlator and software correlator system using GPGPU technology. These OCTAVE-DAS instruments are connected via 10 GigE network with VDIF and VSI specifications. These components have been used for VERA, Japanese VLBI Network (JVN) and EAVN. We will report on current status and results of scientific broad-band (16 Gbps) VLBI test observation using the OCTAVE-DAS.
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