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Measuring deflection of the vertical via local reference point surveying and pointing calibration of VLBI telescope: a case study at Urumqi station
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  • Zhibin Zhang,
  • Xiaohui Ma,
  • Zhongmiao Sun,
  • Ali Zhang,
  • Ye Yuan,
  • Zhengxiong Sun
Zhibin Zhang
Chinese Academy of Sciences,Shanghai Astronomical Observatory

Corresponding Author:[email protected]

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Xiaohui Ma
Xi'an Research Institute of Surveying and Mapping
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Zhongmiao Sun
Xi'an Research Institute of Surveying and Mapping
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Ali Zhang
Xinjiang Astronomical Observatory, CAS
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Ye Yuan
Xinjiang Astronomical Observatory
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Zhengxiong Sun
Xinjiang Astronomical Observatory, Chinese Academy of Sciences
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Deflection of the Vertical (DOV) is vital to astro-geodetic and geophysics research and application. In the Urumqi station, two new non-optical methods including small network coordinate transformation (SNCT) and azimuth-axis inclination inversion (AAII),are proposed to determine the DOV of the VLBI telescope. The generalized expression of the pointing calibration (PC) model regarding of axis-related errors is also presented. Therefore, the PC model and indirect model (IM) used for reference point determination (RPD) are unified by redefining their coordinate system, angle direction, axis related errors. The DOV result of the SNCT method has good agreement with those DOVs solved by the real surveying and other different models, e.g., early Global Navigation Satellite System (GNSS) and leveling measurements (EGL), mass integration model(MIM), etc. Due to the possible asymmetric coverage of calibrating sources in the north-south direction in PC, the north-south DOV component of AAII varies in its value with the surveyed value. However, the west-east DOV component fits well in both direction and magnitude. The proposed methods enable the VLBI telescope to sense the direction of the local plumb line via introducing local leveling. We also establish the connections among VLBI delay observing, RPD, and telescope PC, which has a benefit to muti-tech systematic error identification, monitoring, and correction. The research indicates that, similar to local surveying and VLBI observing, the telescope point calibration can be also taken as a regular technique to monitoring systematic error.