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Processing of VLBI observation in St. Petersburg University Kudryashova Maria Astronomical Institute of Saint Petersburg University.

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Presentation on theme: "Processing of VLBI observation in St. Petersburg University Kudryashova Maria Astronomical Institute of Saint Petersburg University."— Presentation transcript:

1 Processing of VLBI observation in St. Petersburg University Kudryashova Maria Astronomical Institute of Saint Petersburg University

2 Overvew Astronomical Institute structure Laboratory of Astrometry Basic principals of VLBI Analysis of VLBI observations in AI SPb

3 Astronomical Institute structure Laboratories: Active Galaxy Nuclei Observational astrophysics Theoretical astrophysics Solar physics and radioastronomy Stellar dynamics and celestial mechanics Astrometry

4 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)

5 Laboratory of Astrometry -rooms-

6 Laboratory of Astrometry -staff -

7 Laboratory of Astrometry -new telescope- Clear aperture …305 mm (12") Focal length …3048 mm Optical design Schmidt-Cassegrain

8 Basic principles of VLBI -Observables- Observational values:  o - time delay [ns]  /  t - delay rate [ps/s]

9 Basic principles of VLBI -File of observations- DATA IN NGS FORMAT FROM DATA BASE 05OCT06XE_V004 Observed delays and rates into card #2 FORTLEZA AZEL HARTRAO EQUA NYALES AZEL TIGOCONC AZEL KOKEE AZEL WETTZELL AZEL C FORTLEZA HARTRAO I I 109

10 Basic principles of VLBI -fundamental role- CRF Sources positions (!) TRF Station positions velocities EOP Polar Motion (x,y) UT1-UTC (!) Nutation angles (d , d  ) (!)

11 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

12 Observational programs - R1, R4, Int1, Int2-

13 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. )

14 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

15 Analysis of VLBI observations in AI SPb -Methods of parameters estimation- Least square method Kalman Filter Least square collocation method

16 Analysis of VLBI observations in AISPb - Description of solutions for IVS/IERS- Spu00002.eopiSpu0003i.eops Observational programs – NEOS-Intensive … Int1, Int – NEOS-A … 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 

17 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

18 Analysis of VLBI observations in AI SPb - sub-daily EOP-

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