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

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

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

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)

Laboratory of Astrometry -rooms-

Laboratory of Astrometry -staff -

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

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

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

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

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

Observational programs - R1, R4, Int1, Int2-

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. )

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

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

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 

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

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