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S/X receiver for Parkes geodetic VLBI program

S/X receiver for Parkes geodetic VLBI program. О leg Titov ( Geoscience Australia). ATNF, Sydney 29 October 2012. 29 October 2012. IVS astrometric programs.

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S/X receiver for Parkes geodetic VLBI program

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  1. S/X receiver for Parkes geodetic VLBI program Оleg Titov (Geoscience Australia) ATNF, Sydney 29 October 2012 29 October 2012

  2. IVS astrometric programs International VLBI Service (IVS) supports several observational programs (Earth Orientation Parameters; geodesy; astrometry). All in S/X Astrometric programs are designed for improvement and densification of the International Celestial Reference Frame (ICRF2, 2009) Parkes participates in the IVS astrometric programs since 2004, and contributed to ICRF2. Geoscience Australia 29 October 2012

  3. ICRF1 catalogue (1998) 608 sources separated into 3 groups • 212 defining sources with the positional accuracy ~0.25 mas • 294 “non-defining” sources • 102 “other” sources Geoscience Australia Geoscience Australia 29 October 2012 20 June 2012

  4. ICRF2 catalogue (2009) 3414 sources separated into 3 groups • 295 defining sources with the positional accuracy ~0.04 mas • 922 “non-defining” sources • 1217 VCS sources Geoscience Australia Geoscience Australia 29 October 2012

  5. ICRF1 Geoscience Australia 29 October 2012

  6. ICRF2 Geoscience Australia 29 October 2012

  7. ICRF2 7 million group delays were measured for legacy since 1979All done in S/X Geoscience Australia 29 October 2012

  8. Accuracy for 295 ‘defining’ sources Geoscience Australia 29 October 2012

  9. Accuracy for 1217 ‘non-defining’ sources Geoscience Australia 29 October 2012

  10. ICRF2 catalogue (2009) 295 defining sources with the positional accuracy ~0.04 mas We have reached the limit of accuracy to search for hidden systematic effects Geoscience Australia Geoscience Australia 29 October 2012

  11. The Galaxy Geoscience Australia 29 October 2012

  12. Centrifugal acceleration due to rotation of the Solar system around the Galaxy center V V a a Geoscience Australia 29 October 2012

  13. Secular aberration drift Systematic proper motion (dipole effect) caused by the acceleration of the Solar system barycentre P – angle between object and the Galactic centre Geoscience Australia Geoscience Australia 29 October 2012

  14. Analytical expression for the dipole proper motion Geoscience Australia 29 October 2012

  15. Fanselow (1983) Observation Model and Parameter Partials for the JPL VLBI Parameter Estimation Software MASTERFITV1.0, JPL Publication 83-39.Bastian (1995)Eubanks et al (1995)Gwinn et al (1997)Sovers, Jacobs, Fanselow (1998)Kovalevsky (2003)MacMillan (2005)Kopeikin and Makarov (2006) References 29 October 2012

  16. 40 sources observed in more > 1,000 sessions The dipole systematic is visually detected! 29 October 2012

  17. Observed apparent proper motions 29 October 2012

  18. The Dipole obtained from 643 radio sources a = 5.3 ± 1.1 mas/yr toward a = 268 ± 12°, d = -30 ± 13° 29 October 2012

  19. Interim conclusion We are able to detect a tiny systematic proper motion of the reference radio sources (up to 1 μas/year), free of the intrinsic motion caused by the relativistic jets. Potentially, we could study the dynamics of the Universe by the same way as we used to study the dynamics of the Galaxy Geoscience Australia 29 October 2012

  20. Redshift dependence Geoscience Australia 29 October 2012

  21. Quadrupole systematic (2012) Mean square mplitude ~ 4.3 ± 1.4 mas/year Redshift dependent 29 October 2012

  22. Quadrupole systematic Dipole systematic Astrometric stability: 0.2<z<1

  23. Covariance function Consider correlation between two point in sphere, separated by the angular distance P 29 October 2012

  24. One-dimensional covariance function 29 October 2012

  25. One-dimensional covariance function 29 October 2012

  26. One-dimensional covariance function 29 October 2012

  27. Spectra of two proper motion components 29 October 2012

  28. Spectrum of vector proper motion 29 October 2012

  29. Accuracy for 295 ‘defining’ sources Geoscience Australia 29 October 2012

  30. 643 measured proper motions • DE>+40 117 • 0<DE<+40 247 • -40<DE<0 174 • DE<-40 83 • More observations are required, especially, in the southern hemisphere. 29 October 2012

  31. Australian (AuScope) – New Zealand network Geoscience Australia 29 October 2012

  32. 12m Antenna at Patriot 5 deg/sec in azimuth, 1.5 deg/sec in elevation 29 October 2012

  33. Conclusions • Positions of the reference radio sources are likely to be affected by positional instabilities, random or systematic • Cosmologic signals may be presented. • More observations are required, especially, in the southern hemisphere. 29 October 2012

  34. Plans • ICRF3 to be approved by IAU GA in 2018 • IVS is planning to run am intensive astrometric program since 1, July, 2013. • Southern Hemisphere is the area of special attention • AuScope network to play a key role • Parkes (with S/X receiver) is very important for observing of weak quasars for ICRF densification 29 October 2012

  35. Thank you! 29 October 2012

  36. Reference frames Inertial – no acceleration of the origin, no rotation of reference axes Non-inertial – non-zero acceleration, rotation of reference axes is permitted Quasi-inertial – acceleration of the origin is permitted, no rotation of references axes Geoscience Australia 29 October 2012

  37. ICRS definition Assumption (1995)“The reference radio sources have no measurable proper motion[at the level of precision achieved to 1995]” The secular acceleration drift (dipole effect) is not considered by the current ICRS assumptions and IERS conventions - tbd Geoscience Australia 29 October 2012

  38. Proper motion in the expanding Universe (Kristian and Sachs, 1966) “Observations in cosmology” σ – Shear ω- Rotation E – electric-type gravitational waves H – magnetic-type gravitational waves 29 October 2012

  39. The Dipole obtained from 555 radio sources a = 6.4 ± 1.5 mas/yr toward a = 263 ± 11°, d = -20 ± 12° 29 October 2012

  40. Solutionof 2010 [Titov, Lambert, Gontier, A&A(2011), 529, A91]555 sources 0.7 +/- 1.1 μas/y -5.9 +/- 1.2 μas/y -2.2 +/- 1.2 μas/yAmplitude 6.4 +/- 1.3 μas/yRA = 263 +/- 11DE = -20 +/- 12chi-sq = 1.5wrms = 23.0μas/y Solutionof 2012643 sources 0.2 +/- 1.0 μas/y -4.5 +/- 1.1 μas/y -2.6 +/- 1.2 μas/yAmplitude 5.3 +/- 1.1 μas/yRA = 268 +/- 12DE = -30 +/- 13chi-sq = 1.3wrms = 20.8μas/y Geoscience Australia 29 October 2012

  41. Conclusions • The dipole effect does exist and is aligned with the theoretical prophecy. • More distant radio sources (z>1.134) look less stable. It is important for future radio ICRF realizations. • Cosmologic signals may be presented. • Spectroscopic observations are essential. 29 October 2012

  42. Part II • Spectroscopic observations of reference radio sources (mostly in the southern hemisphere) 29 October 2012

  43. Team members:David Jauncey (ATNF, CSIRO)Dick Hunstead, Helen Johnston (Uni of Sydney)Tapio Pursimo (Nordic Optical Telescope)Zinovy Malkin, Kirill Maslennikov, Alexandra Boldycheva (Pulkovo Observatory)Laura Stanford (Geoscience Australia) 29 October 2012

  44. How to implement the effect? 29 October 2012

  45. 1. Introduce non-zero systematic proper motion at the level of IAU Resolutions Two ways (at least) 2. Incorporate the galactocentric acceleration to the conventional group delay model (IERS Conventions) 29 October 2012

  46. Conventional group delay model Titov, Astronomy Report (2011), 55(1), 95 29 October 2012

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