4:15 PM - 4:30 PM
[SGD01-22] SLR/GNSS observations and co-location survey at the Shimosato Hydrographic Observatory
Keywords:Satellite Laser Ranging, GNSS, Global Geodetic Observation System, Co-location survey
The Japan Coast Guard (JCG) operates Satellite Laser Ranging (SLR) observation at the Shimosato Hydrographic Observatory (SHO) since 1982. SLR observation results obtained at the SHO are submitted to the International Laser Ranging Service (ILRS), contributing to the development of the International Terrestrial Reference Frame (ITRF). SHO also conducts continuous GNSS observation at site “SMST”, which is one of the sites of the International GNSS Service (IGS). SHO, operating two types of space geodetic techniques, contributes to international geodetic frameworks such as the Global Geodetic Observing System (GGOS).
In order to construct a global earth-centered reference frame, it is necessary to link the reference frames obtained by using different space geodetic techniques. Thus, observation sites such as SHO that operate multiple space geodetic techniques, which function as co-location sites, are necessary for constructing a reference frame. At co-location sites, measurements using different techniques must be linked together by precisely determining the local tie between the reference points of the techniques.
In November 2020, the JCG and the Geospatial Information Authority of Japan (GSI), which has a prolonged experience of co-locating VLBI sites, have performed a co-location survey at the SHO to determine the local tie between the fixed point of the SLR telescope (SISL) and the GNSS station monument (SMST). In the survey, we mounted several targets on the SLR telescope, which we observed from four reference sites that were temporarily set around the observatory. To measure the fixed point of the SLR telescope, we rotated the telescope along the azimuth and the elevation axes at fixed intervals, observing the target positions for each rotation angle. The measured target positions form arcs around the rotation axes of the telescope, from which we can estimate the intersection of the axes (i.e., the fixed point of the SLR telescope). We also conducted levelling between the antenna reference point of the GNSS station and the center of the nasmyth mirror of the SLR telescope, which is the designed fixed point. For the calculation of the local tie, we used the software pyaxis (https://github.com/linz/python-linz-pyaxis), developed by Land Information New Zealand (LINZ).
In this presentation, we will present the results of the analyses of the SLR and GNSS data measured at the SHO. We will also show the methods of our co-location survey and the local tie calculation described above, and the estimated local tie vector.
Acknowledgements: Dr. Otsubo of the Hitotsubashi University has provided the SLR analysis software “C5++” and adjusted the data/parameters for SHO’s data analysis in this study.
In order to construct a global earth-centered reference frame, it is necessary to link the reference frames obtained by using different space geodetic techniques. Thus, observation sites such as SHO that operate multiple space geodetic techniques, which function as co-location sites, are necessary for constructing a reference frame. At co-location sites, measurements using different techniques must be linked together by precisely determining the local tie between the reference points of the techniques.
In November 2020, the JCG and the Geospatial Information Authority of Japan (GSI), which has a prolonged experience of co-locating VLBI sites, have performed a co-location survey at the SHO to determine the local tie between the fixed point of the SLR telescope (SISL) and the GNSS station monument (SMST). In the survey, we mounted several targets on the SLR telescope, which we observed from four reference sites that were temporarily set around the observatory. To measure the fixed point of the SLR telescope, we rotated the telescope along the azimuth and the elevation axes at fixed intervals, observing the target positions for each rotation angle. The measured target positions form arcs around the rotation axes of the telescope, from which we can estimate the intersection of the axes (i.e., the fixed point of the SLR telescope). We also conducted levelling between the antenna reference point of the GNSS station and the center of the nasmyth mirror of the SLR telescope, which is the designed fixed point. For the calculation of the local tie, we used the software pyaxis (https://github.com/linz/python-linz-pyaxis), developed by Land Information New Zealand (LINZ).
In this presentation, we will present the results of the analyses of the SLR and GNSS data measured at the SHO. We will also show the methods of our co-location survey and the local tie calculation described above, and the estimated local tie vector.
Acknowledgements: Dr. Otsubo of the Hitotsubashi University has provided the SLR analysis software “C5++” and adjusted the data/parameters for SHO’s data analysis in this study.