摘要
The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the development of synchronous tracking of fixed targets on telescopes during the observing, the RPs also can be determined in near real time based on a frame defined by other techniques. These opportunities provide us a possibility to explore the high geodetic resolution of VGOS telescopes. We design a thermal variation in RP as true values, and schedule a synchronous session of VGOS and target point(TP) series observing. Then VGOS delays and TP series are simulated and solved via piecewise functions. The results show that the accuracy of vertical component of the RP could be determined at an accuracy of 0.5 ± 0.3 mm in an hour using TP series, whereas the vertical components of RP solved by using VGOS delay measurements have a greater uncertainty due to the random error in the simulated atmosphere and bad radio source sky coverage in a shorter time interval. Some details in the data processing and accuracy evaluation are also introduced.
The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the development of synchronous tracking of fixed targets on telescopes during the observing, the RPs also can be determined in near real time based on a frame defined by other techniques. These opportunities provide us a possibility to explore the high geodetic resolution of VGOS telescopes. We design a thermal variation in RP as true values, and schedule a synchronous session of VGOS and target point(TP) series observing. Then VGOS delays and TP series are simulated and solved via piecewise functions. The results show that the accuracy of vertical component of the RP could be determined at an accuracy of 0.5 ± 0.3 mm in an hour using TP series, whereas the vertical components of RP solved by using VGOS delay measurements have a greater uncertainty due to the random error in the simulated atmosphere and bad radio source sky coverage in a shorter time interval. Some details in the data processing and accuracy evaluation are also introduced.
引文
[1]H. Schuh, D. Behrend, VLBI:a fascinating technique for geodesy and astrometry, J. Geodyn. 61(2012)68-80. https://doi.org/10.1016/j.jog.2012.07.007.
[2]P.M. Mathews, T.A. Herring, B.A. Buffett, Modeling of nutation and precession:new nutation series for nonrigid Earth and insights into the Earth's interior, J. Geophys. Res. Solid Earth 107(B4)(2002). https://doi.org/10.1029/2001JB000390.
[3]J. Sun, C.L Dai, N.C. Jian, et al., Investigation of stronger diurnal ERP signals in summer derived from the VLBI CONT08 campaign, Chin. Sci. Bull. 55(2010).https://doi.org/10.1007/s11434-010-4076-5.
[4]A. Niell, A. Whitney, B. Petrachenko, et al., VLBI2010:Current and Fu-ture Requirements for Geodetic VLBI Systems, International VLBI Service for Geodesy and Astrometry, 2005, pp. 13-40.
[5]B. Petrachenko, A. Niell, D. Behrend, et al., Design Aspects of the VLBI2010System, Progress Report of the IVS VLBI2010 Committee. NASA/TM-2009-214180, 2009 https://space-geodesy.nasa.gov/docs/2009/TM-2009-214180.pdf.
[6]J. Dawson, P. Sarti, G.M. Johnston, et al., Indirect approach to invariant point determination for SLR and VLBI systems:an assessment, J. Geod. 81(6-8)(2007)433-441. https://doi.org/10.1007/s00190-006-0125-x.
[7]J.L Li, J.W. Zhang, L. Guo, On the monitoring model of reference point of VLBI antenna, Sci. China Phys. Mech. Astron. 56(10)(2013)1987-1994. https://doi.org/10.1007/s11433-013-5171-9.
[8]M. Losler, M. Hennes, An innovative mathematical solution for a time-efficient IVS reference point determination, Meas. Changes(2008)12-15.
[9]U. Kallio, M. Poutanen, Can we really promise a mm-accuracy for the local ties on a geo-VLBI antenna, in:S. Kenyon, M. Pacino, U. Marti(Eds.), Geodesy for Planet Earth. Proceedings of the 2009 IAG Symposium, Buenos Aires,Argentina, 31 August 314 September 2009 vol. 136, International Association of Geodesy Symposia, Springer, 2012, p. 3542. https://doi.org/10.1007/978-3-642-20338-1 5.
[10]G.R. Pan, H.F. Li, A new test method based on space vector in 3D circle fit-ting,J. Geodesy Geodyn. 30(4)(2010)106-108, https://doi.org/10.3969/j.issn.1671-5942.2010.04.020(in Chinese).
[11]Z. Altamimi, X. Collilieux, L. M eivier, ITRF2008:an improved solution of the international terrestrial reference frame, J. Geod. 85(2011)457-473. https://doi.org/10.1007/s00190-011-0444-4.
[12]J. Ray, Z. Altamimi, Evaluation of co-location ties relating the VLBI and GPS reference frames, J. Geod. 79(4-5)(2005)189-195. https://doi.org/10.1007/s00190-005-0456-z.
[13]M. Losler, R. Haas, C. Eschelbach, Automated and continual determination of radio telescope reference points with sub-mm accuracy:results from a campaign at the Onsala space observatory, J. Geod. 87(8)(2013)791-804.https://doi.org/10.1007/s00190-013-0647-y.
[14]T. Ning, R. Haas, G. Elgered, Determination of the local tie vector between the VLBI and GNSS reference points at Onsala using GPS measurements, J. Geod.89(7)(2015)711-723. https://doi.org/10.1007/s00190-015-0809-1.
[15]M. Losler, R. Haas, C. Eschelbach, Terrestrial monitoring of a radio telescope reference point using comprehensive uncertainty budgeting, J. Geod. 90(5)(2016)467-486. https://doi.org/10.1007/s00190-016-0887-8.
[16]Z.B. Zhang, X. Liu, A VLBI baseline post-adjustment approach for station velocity estimation in Eurasian continent, J. Adv. Space Res. 54(8)(2014)1563-1570. https://doi.org/10.1016/j.asr.2014.06.032.
[17]J. Sun, J. B(o|¨)hm, T. Nilsson, et al., New VLBI2010 scheduling strategies and implications on the terrestrial reference frames, J. Geod. 88(5)(2014)449-461. https://doi.org/10.1007/s00190-014-0697-9.
[18]H. McGinnis, G. Gale, R. Levy, Estimated displacements for the VLBI reference point of the DSS 14 antenna, DSN Prog. Rep. 42-41(1977)218-225.
[19]A. Nothnagel, M. Pilhatsch, Investigations of thermal height changes of geodetic VLBI radio telescopes, in:Proceedings of the 10th Working Meeting on European VLBI for Geodesy and Astrometry, 1995, pp. 121-133.
[20]J. Wresnik, R. Haas, J. B(o|¨)hm, et al., Modeling thermal deformation of VLBI antennas with a new temperature model, J. Geod. 81(2007)423431. https://doi.org/10.1007/s00190-006-0120-2.
[21]R. Zernecke, Seasonal variations in height demonstrated at the radio telescope reference point, in:Proceedings of the 13th Working Meeting on European VLBI for Geodesy and Astrometry, 1999, pp. 15-18.
[22]A. Nothnagel, Conventions on thermal expansion modelling of radio telescopes for geodetic and astrometric VLBI, J. Geod. 83(8)(2009)787-792.https://doi.org/10.1007/s00190-008-0284-z.
[23]T. Nilsson, M. Karbon, B. Soja, et al., Atmospheric modeling for co-located VLBI antennas and twin telescopes, J. Geod. 89(7)(2015)1-11. https://doi.org/10.1007/s00190-015-0804-6.
[24]J. Bohm, S. Bohm, T. Nilsson, et al., The New Vienna VLBI Software VieVS,Geodesy for Planet Earth, Springer Berlin Heidelberg, 2012, pp. 1007-1011.https://doi.org/10.1007/978-3-642-20338-1 126.
[25]M. L(o|¨)sler, Reference point determination with a new mathematical model at the 20 m VLBI radio telescope in Wettzell, J. Appl. Geod. 2(2008)233238.https://doi.org/10.1515/JAG.2008.026.
[26]K. Teke, J. B(o|¨)hm, H. Spicakova, et al., Piecewise Linear Offsets for VLBI Parameter Estimation. EVGA Working Meeting&IVS Analysis Workshop, IVS,Anniversary Celebration, 2009.
[27]K.R. Koch, Robust estimations for the nonlinear Gauss Helmert model by the expectation maximization algorithm, J. Geod. 88(3)(2014)263-271. https://doi.org/10.1007/s00190-013-0681-9.
[28]R.N. Treuhaft, Lanyi GE the effect of the dynamic wet troposphere on radio interferometric measurements, Radio Sci. 22(2)(1987)251265. https://doi.org/10.1029/RS022i002p00251.
[29]C.S. Jacobs, Modeling antenna effects for mm level VLBI, Geod. VLBI:Monit.Glob. Change 1(1991), 159-159.
[30]O.J. Sovers, J.L. Fanselow, C.S. Jacobs, Astrometry and geodesy with radio interferometry:experiments, models, results, Rev. Mod. Phys. 70(4)(1997)1393-1454. https://doi.org/10.1103/RevModPhys.70.1393.
[31]P. Sarti, C. Abbondanza, L. Vittuari, Gravity-dependent signal path variation in a large VLBI telescope modelled with a combination of surveying methods,J. Geod. 83(11)(2009)1115-1126. https://doi.org/10.1007/s00190-009-0331-4.
[32]P. Sarti, L. Vittuari, C. Abbondanza, Laser scanner and terrestrial surveying applied to gravitational deformation monitoring of large VLBI telescopes primary reflector, J. Survey Eng. 135(4)(2009)136-148. https://doi.org/10.1061/(ASCE)SU. 1943-5428.0000008.
[33]P. Sarti, C. Abbondanza, L. Petrov, M. Negusini, Height bias and scale effect induced by antenna gravitational deformations in geodetic VLBI data analysis,J. Geod. 85(1)(2011)1-8. https://doi.org/10.1007/s00190-010-0410-6.
[34]C. Abbondanza, P. Sarti, Impact of network geometry, observation schemes and telescope structure deformations on local ties:simulations applied to Sardinia radio telescope, J. Geod. 86(3)(2012)181-192. https://doi.org/10.1007/s00190-011-0507-6.
1 http://dels.nas.edu/Report/Precise-Geodetic-Infrastructure-NationalRequirements/12954.