Status of Ishioka Geodetic Observing Station

The Ishioka 13-m telescope at the Ishioka Geodetic Observing Station (hereafter Ishioka station), operated by the Geospatial Information Authority of Japan, has participated in the IVS sessions since 2015. Currently, the Ishioka station is involved in VGOS observations for several months a year and in legacy S/X observations for the rest of the year by switching their respective receivers. The VGOS period, which was initially three months, was extended to six months in 2022.

We at the Ishioka station are actively involved in the following aspects: the issue of polarization, the installation of new recording systems and local-tie surveys. Firstly, we are now exploring measures that could help receive both VGOS and S/X bands by the broad-band receiver currently used for only VGOS observations. The measures will help us to eliminate the interruption period necessary to switch receivers. Since the problem of RFI in the S-band was fixed by installing the superconducting filters in the receiver, the remaining challenge is how to handle the polarization. This is because the polarization is different between VGOS and S/X observations. In addition to the method conducted by the IVS in which the correlator processes both linear and circular polarizations, we are investigating a way of converting linear polarizations to circular one at the recording system. Secondly, we are preparing to install a new sampler DBBC3 and a recording system FlexBuff. At the Ishioka station, ADS3000+ developed by NICT is currently used, but the issue is that new servers connectable to it are no longer available. We will begin adjusting the new systems after they arrive in March 2023 and will use them as soon as possible.

Thirdly, we are carrying out local-tie surveys regularly to estimate the local-tie vector between the reference points of the telescopes and the IGS GNSS station operated at the Ishioka station. The results of the 2018 and 2020 surveys were submitted to the IERS to contribute to the construction of ITRF2020. The surveys were also conducted in 2021 and 2022 and they are under calculation.

In this presentation, we will report the current status and near future prospects of the Ishioka Geodetic Observing Station.