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Australian Government Geoscience Australia. Statistical properties of CRF solution from VLBI data analysis Oleg Titov. GAIA-2005, Dresden, 15-16, September 2005. 03/000. Geoscience Australia. 15 September 2005. Selection of radiosources. A set of reference quasars to be fixed.

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03/000

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  1. Australian Government Geoscience Australia Statistical properties of CRF solution from VLBI data analysis Oleg Titov GAIA-2005, Dresden, 15-16, September 2005 03/000

  2. Geoscience Australia 15 September 2005

  3. Selection of radiosources A set of reference quasars to be fixed • ICRF (Ma et al., 1998) • Feissel-Vernier (2003) • Structure index (Fey & Charlot, 1997; 2000) Geoscience Australia 15 September 2005

  4. ICRF catalogue (1998) 608 sources separated into 3 groups • 212 defining sources with position accuracy ~0.4 mas • 294 candidate sources • 102 other sources Geoscience Australia 15 September 2005

  5. ICRF defining sources Geoscience Australia 15 September 2005

  6. Feissel-Vernier (2003) 362 pre-selected sources separated into 4 groups • 199 ‘stable’ sources (groups 1 and 2) • 7 ‘unstable’ sources (group 3) • 156 ‘highly unstable or drifting’ sources (group 4) Geoscience Australia 15 September 2005

  7. The lists are not consistent !!! 81 ‘stable’ sources are ‘defining’ and 49 ‘other’ Geoscience Australia 15 September 2005

  8. ICRF source instability(quasar 2201+315) Geoscience Australia 15 September 2005

  9. ICRF source instability(quasar 2201+315, in plane, 2001-2004) other stable # 3 Shift ~1.2 mas ( ~3.5 cm ) Geoscience Australia 15 September 2005

  10. ICRF source instability(structure) Geoscience Australia 15 September 2005

  11. ICRF source instability(structure) Geoscience Australia 15 September 2005

  12. ICRF source instability(flux density by Esko Valtaoja, Turku Observatory) Geoscience Australia 15 September 2005

  13. - GSFC, USNO, BKG, MAO, AUS, ... Global CRF solutions from VLBI Geoscience Australia 15 September 2005

  14. - AUS (Geoscience Australia)- OCCAM v 6.1- VLBI data from 1979 till 2004- 859 quasars in initial catalogue- Global CRF solutions Geoscience Australia 15 September 2005

  15. All radiosources are separated into 3 groups1. Global imposed by NNR (ICRF)2. Global without NNR3. Local Global VLBI solutions Geoscience Australia 15 September 2005

  16. All radiosources are separated into 3 groups1. 207 ICRF-Ext.2 ‘defining’ sources2. 199 ‘stable’ sources 3. 120 ‘overstable’ sources Global VLBI solutions Geoscience Australia 15 September 2005

  17. All networks are separated into 2 groups1. NEOS-A/IRIS-A in 1983-2001 limited number (332) of comparatively bright sources presumably in the Northern hemisphere (δ>-30°)2. all other networks (659 sources) Global VLBI solutions Geoscience Australia 15 September 2005

  18. The acceleration effect estimates are used as indicator for the CRF solutions stability3,208.197 time delays Global VLBI solutions Geoscience Australia 15 September 2005

  19. Acceleration of the Solar system due to Galaxy rotation Geoscience Australia 15 September 2005

  20. Direct adjustment (one-step)(source positions are estimated as global parameters for stable sources and dailyparameters for unstable sources) 2. From apparent proper motion (two-step)(source positions and apparent proper motions are estimated as global parametersfor selected sources) Acceleration of the Solar system due to Galaxy rotation Geoscience Australia 15 September 2005

  21. Direct adjustmentAUS1979-20043199 sessions (24 hour)3,208.197 time delays Global CRF solutions Geoscience Australia 15 September 2005

  22. Global VLBI solutions(the number of global radiosources) Black – all data; red – no IRIS-A/NEOS-A data in 1983-2001 Geoscience Australia 15 September 2005

  23. Global VLBI solutions(Galaxy Acceleration, μas/y) Black – all data; red – no IRIS-A/NEOS-A data in 1983-2001 Geoscience Australia 15 September 2005

  24. From proper motionDaily time series of ALL quasars in 1979-2005 separated into three equal groups143 apparent proper motion (at least 20 sessions with at least 20 scans) including stable and unstable. USNO global VLBI solution 2005 Geoscience Australia 15 September 2005

  25. 106 radiosource proper motions were used for estimation of the Galaxy acceleration effect USNO global VLBI solution 2005 V = 9.7 +/- 2.3 μas/y Geoscience Australia 15 September 2005

  26. USNO global VLBI solution 2005 Geoscience Australia 15 September 2005

  27. Problems extended and stable radiosource can become unstable any time; positions of extended radiosources observed by different networks can be inconsistent; Geoscience Australia 19 September 2005

  28. Conclusion • VLBI data before 1990 are not reliable2. VLBI subnetworks produce different results3. New strategy for selection of stable radiosources is wanted4. More radiosource are wanted5. Effect of the Galaxy acceleration is volatile6. Hopefully, it can be detected by 2010 Geoscience Australia 15 September 2005

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