VLBI-GNSS co-location survey at the Ishioka Geodetic Observing Station in 2018 and 2020

Geospatial Information Authority of Japan has a VLBI antenna (ISHIOKA) and an IGS station (ISHI) at the Ishioka Geodetic Observing Station. The Ishioka VLBI antenna has participated in the IVS sessions and IGS station ISHI has continuously provided the GNSS data.

We conducted co-location surveys in November 2018 and September 2020 to determine a local tie vector between the Ishioka VLBI antenna and the IGS station ISHI. In the surveys, we determined the position of ISHI w.r.t. four surrounding reference pillars by angle/distance measurements and leveling. To determine the position of the VLBI antenna reference point w.r.t. the pillars, we adopted the “inside method” (Munekane, 2019), where the position of the VLBI reference point is determined by observing mirror installed inside the AZ cabin from the fixed point inside the cabin; its position is determined by angle/distance measurements from the pillars. We plan to finish the calculation early this year and submit the results to IERS ITRS Center so as to contribute to the ITRF2020.

In this presentation, we will outline the inside method and compare the results in 2018 and 2020.