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Processing of VLBI observation in St. Petersburg University Kudryashova Maria Astronomical Institute of Saint Petersburg University
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Overvew Astronomical Institute structure Laboratory of Astrometry Basic principals of VLBI Analysis of VLBI observations in AI SPb
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Astronomical Institute structure Laboratories: Active Galaxy Nuclei Observational astrophysics Theoretical astrophysics Solar physics and radioastronomy Stellar dynamics and celestial mechanics Astrometry
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Laboratory of Astrometry -areas of investigation - Analysis of stars catalogues Study of Earth rotation GPS observations (2003, S.D. Petrov) Analysis of VLBI observation (1998, O.A. Titov)
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Laboratory of Astrometry -rooms-
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Laboratory of Astrometry -staff -
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Laboratory of Astrometry -new telescope- Clear aperture...........................................…305 mm (12") Focal length.............................................…3048 mm Optical design..............................................Schmidt-Cassegrain
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Basic principles of VLBI -Observables- Observational values: o - time delay [ns] / t - delay rate [ps/s]
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Basic principles of VLBI -File of observations- DATA IN NGS FORMAT FROM DATA BASE 05OCT06XE_V004 Observed delays and rates into card #2 FORTLEZA 4985370.04800 -3955020.32000 -428472.30600 AZEL.00000 HARTRAO 5085442.79600 2668263.49800 -2768697.04300 EQUA 6.69500 NYALES20 1202462.76100 252734.40400 6237766.01300 AZEL.50800 TIGOCONC 1492054.25700 -4887960.95600 -3803541.32000 AZEL.00000 KOKEE -5543837.62100 -2054567.85200 2387851.92200 AZEL.50800 WETTZELL 4075539.89500 931735.27000 4801629.35500 AZEL.00000 1741-038 17 43 58.856137 - 3 50 4.616680 1357+769 13 57 55.371519 76 43 21.051110 1611+343 16 13 41.064249 34 12 47.909090 2318+049 23 20 44.856598 5 13 49.952660 2243-123 22 46 18.231976 -12 6 51.277340 3C418 20 38 37.034755 51 19 12.662690 1749+096 17 51 32.818573 9 39 0.728510 FORTLEZA HARTRAO 1741-038 2005 10 06 18 30 49.0000000000 101 9236929.27028809.01143 1441422.4850029480.01502 0 I 102.00115.00000.00000.00000 -.361142653441616 0. 103.00.0.00.0.00.0.00.0 104.10331 -.02731.00000.00000.00000.00000 105 20.000 16.358 1010.000 869.502 60.000 40.751 0 0 106 2.4571482880.00433 -.0494891659.00389 0 108 9236929.27028809.03096 1441422.4850029480.16652 0 I 109
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Basic principles of VLBI -fundamental role- CRF Sources positions (!) TRF Station positions velocities EOP Polar Motion (x,y) UT1-UTC (!) Nutation angles (d , d ) (!)
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Basic principles of VLBI -observational programs- Earth Orientation Parameters (EOP): Terrestrial Reference Frame (TRF): Celestial Reference Frame (CRF): Monthly sessions to investigate instrumental effects : IVS-R1, IVS-R4 IVS-INT1, IVS-INT2 IVS-E3 IVS-T2 (RDV) IVS-CRF (RDV) IVS-R&D
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Observational programs - R1, R4, Int1, Int2-
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Basic principles of VLBI -processing of VLBI- Calculation of the model of VLBI observable (description of procedures could be found in IERS Conventions) - c Estimation of parameters (LS method, least- square collocation method LSCM, Kalman filter, etc.) = o - c = c / p i p i + w, p i – parameters under estimations (EOP, stations and radiosources coordinates, etc. )
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Basic principles of VLBI -modeling of observable- x i,y i,z i, i=1,.., N - stations coordinates in TRF (N=2-10) should be modified for Earth-fixed effects (tides, loading, tectonic motion, etc.) j j, j=1,.., M – radiosources coordinates in CRF (M~60) EOP – a priory values of x,y, UT1-UTC, d ,d from IERS C04 c c = - k Q (r 2 - r 1 ) + …. k – unit vector from the barycenter to the radiosource; r i – position of station “ i “ in TRF; Q – transformation matrix from Terrestrial to Celestial Reference Frame
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Analysis of VLBI observations in AI SPb -Methods of parameters estimation- Least square method Kalman Filter Least square collocation method
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Analysis of VLBI observations in AISPb - Description of solutions for IVS/IERS- Spu00002.eopiSpu0003i.eops Observational programs 09.1997 – 12.2001 NEOS-Intensive 01.2002 -… Int1, Int2 01.1989 – 12.2001 NEOS-A 01.2002 -… R1,R4 Number of session (days between sess.) 6-7 sess. per week (1-2 day) 2 sess. per week (2-3 day) Duration of session1 hour24-hours Parameters under estimation UT1-UTC x, y, UT1-UTC, d , d
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Analysis of VLBI observations in AISPb -S olution for CRF, TRF, sub-daily EOP- Observational programs (1989-now): NEOS-A, CORE-A, Cont94, Cont96, Cont02, R1,R4 … Time lag between the sessions: 7-1 day Duration of session: 24 hours Parameters under estimation: daily parameters - TRF, d , d ; sub-daily parameters - x, y, UT1-UTC Number of estimation: 1 per 2-5 min
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Analysis of VLBI observations in AI SPb - sub-daily EOP-
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