Processing of VLBI observation in St. Petersburg University

Kudryashova MariaAstronomical Institute of Saint Petersburg University

Overvew

Astronomical Institute structureLaboratory of AstrometryBasic principals of VLBI Analysis of VLBI observations in AI SPb

Astronomical Institute structureLaboratories: 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 cataloguesStudy of Earth rotationGPS 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 mmOptical 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 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

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-R4IVS-INT1, IVS-INT2IVS-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/pi pi + w, pi – parameters under estimations (EOP, stations and radiosources coordinates, etc. )

Basic principles of VLBI -modeling of observable-

xi,yi,zi, i=1,.., N - stations coordinates in TRF (N=2-10) should be modified for Earth-fixed effects (tides, loading, tectonic motion, etc.)

jj , j=1, .., M – radiosources coordinates in CRF (M~60)

EOP – a priory values of x,y, UT1-UTC, d,d from IERS C04

cc = - k Q (r2 - r1 ) + …. k – unit vector from the barycenter to the radiosource; ri – 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 methodKalman Filter Least square collocation method

Analysis of VLBI observations in AISPb -Description of solutions for IVS/IERS-

Spu00002.eopi Spu0003i.eopsObservational programs

09.1997 – 12.2001 NEOS-Intensive01.2002 -… 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 session 1 hour 24-hoursParameters under estimation

UT1-UTC x, y, UT1-UTC, d, d

Analysis of VLBI observations in AISPb -Solution 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 dayDuration of session: 24 hoursParameters 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-