processing of vlbi observation in st. petersburg university kudryashova maria astronomical institute...
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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 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 cataloguesStudy of Earth rotationGPS observations (2003, S.D. Petrov)Analysis of VLBI observation (1998, O.A. Titov)
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
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.eops
Observational 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-hours
Parameters 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