03/000 vlbi network design australian government geoscience australia ngrs workshop, 1-2 february,...
DESCRIPTION
ICRF catalogue (1998) Geoscience Australia 17 August defining sources with position accuracy ~0.4 mas candidate sources other sources 608 sources separated into 3 groupsTRANSCRIPT
03/000
VLBI network design
Australian Government
Geoscience Australia
NGRS Workshop, 1-2 February, Canberra
Geoscience
Australia17 August 2005
ICRF catalogue (1998)
Geoscience Australia
17 August 2005
1.212 defining sources with position accuracy ~0.4 mas
2.294 candidate sources
3.102 other sources
608 sources separated into 3 groups
Radiotelescopes in Australia
Geoscience Australia
28 June 2004
ICRF defining sources
Geoscience Australia
17 August 2005
ICRF source instability(quasar 2145+067)
Geoscience Australia
17 August 2005
Year
1994 1996 1998 2000 2002 2004
mse
c
-0.10
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
Daily estimatesApproximation
Instability~0.2 mas( 6 mm )
ICRF source instability
Geoscience Australia
17 August 2005
It is important to monitor all radiosources to mitigate the effect of instability
About 60 defining sources from the ICRF catalogue are appeared to be unstable!
New ICRF realization wanted now
Geoscience
Australia17 August 2005
Radiotelescopes in Australia
Geoscience Australia
17 August 2005
Geoscience
Australia17 August 2005
Hobart,26-meterantenna
Too far from all other telescopes;Limited amount of defining sources in southern hemisphere – problems with scheduling;Slow slew rate (1 deg/sec) – little data
Problem
Geoscience Australia
17 August 2005
- set of radiosources to be fixed (212 defining sources);
- if unstable radiosources are fixed the geodetic results will be corrupted;
- effect of the instability of the fixed radiosources on the TRF solution has never been studied!
Procedure
Geoscience Australia
17 August 2005
- two global VLBI solutions have been obtained by identical way;
- Solution 1: 207 ICRF defining sources;
- Solution 2: 199 ‘stable’ sources (Feissel-Vernier);
- daily TRF solutions have been obtained for Sol #1 and #2 providing two sets of time series of VLBI site geodetic positions;
- differences of the daily geodetic positions were calculated;
- measure of discrepancy between two solution
TRF daily difference time series
Geoscience Australia
17 August 2005
Height differencesWestford
Year
1980 1985 1990 1995 2000 2005
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Height componentOnsala60
Year
1976 1980 1984 1988 1992 1996 2000 2004m
eter
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Geoscience
Australia17 August 2005
Heght differencesNy-Alesund
Year
1994 1996 1998 2000 2002 2004 2006m
eter
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
TRF daily difference time series
Height componentKokee
Year
1992 1994 1996 1998 2000 2002 2004 2006
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Geoscience
Australia17 August 2005
TRF daily difference time series
Height componentTigoconc
Year
2002 2003 2004 2005 2006
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Height positionSvetloe
Year
2003.0 2003.5 2004.0 2004.5 2005.0 2005.5
met
er-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Geoscience
Australia17 August 2005
TRF daily difference time series
Height component,Hobart
Year
1988 1992 1996 2000 2004
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Height componentHartrao
Year
1984 1988 1992 1996 2000 2004
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
wrms and offset of the TRF solution
Geoscience Australia
17 August 2005
Station Latitude(º)
wrms (mm)
Offset(mm)
height latitude longitude height latitude longitude
Algopark 46 5.5 3.0 2.1 0.9 +/- 0.3 0.2 +/- 0.2 0.1 +/- 0.1
DSS45 -35 13.5 9.7 4.6 3.0 +/- 1.7 -0.5 +/- 1.2 -0.7 +/- 0.6
Fortaleza -4 8.6 4.7 3.7 -1.2 +/- 0.4 -0.5 +/- 0.2 0.0 +/- 0.2
Hartrao -25 15.4 7.2 5.2 -1.6 +/- 0.9 -1.4 +/- 0.5 0.2 +/- 0.3
Hobart26 -43 20.4 10.2 9.3 10.6 +/- 1.4 -3.9 +/- 0.7 -0.8 +/- 0.6
Kokee 22 4.8 3.1 3.4 -0.2 +/- 0.2 0.6 +/- 0.1 0.1 +/- 0.1
Medicina 45 3.5 2.7 1.7 0.6 +/- 0.4 0.1 +/- 0.3 -0.3 +/- 0.2
Ny-Alesund 79 3.5 1.4 1.5 -0.3 +/- 0.3 0.0 +/- 0.1 -0.2 +/- 0.1
O’Higgins -63 11.8 6.2 5.9 1.9 +/- 1.8 1.9 +/- 0.9 -0.6 +/- 0.9
Onsala60 57 3.2 2.0 2.1 0.0 +/- 0.1 0.1 +/- 0.1 -0.1 +/- 0.1
Seshan25 31 7.2 2.7 3.3 -0.2 +/- 1.8 0.3 +/- 0.7 -0.2 +/- 0.8
Svetloe 60 4.4 3.9 1.6 -6.9 +/- 7.6 -6.9 +/- 7.5 -3.1 +/- 3.0
Tigoconc -37 16.3 9.4 4.9 24.3 +/- 8.5 -17.8 +/- 4.4 2.7 +/- 2.9
Westford 43 5.4 2.9 2.6 1.0 +/- 0.1 0.5 +/- 0.1 0.0 +/- 0.1
Wettzell 49 4.7 3.0 2.4 0.0 +/- 0.1 0.6 +/- 0.1 -0.4 +/- 0.1
Geoscience
Australia17 August 2005
Effect on the TRF quality (wrms vs latitude)
height component wrms vs latitude
latitude
-90 -60 -30 0 30 60 90
mm
0
5
10
15
20
25
Geoscience
Australia17 August 2005
Hobart daily difference time series
Height component,Hobart
Year
1988 1992 1996 2000 2004
met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
The number of observations per session
0 100 200 300 400 500 600
Met
er
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Hobart’s problem
Geoscience Australia
17 August 2005
- poor reference sources due to geographical location
- insufficient amount of data due to low slew rate
Hobart’s problem solution
Geoscience Australia
17 August 2005
- ICRF (0.1 mas)
ITRF (1 mm)
high slew rate dish
IVS
Australian
more data
more sources
Australian geodetic datum
better reference sourcepositions
GPS
SLR
Conclusion
Geoscience Australia
17 August 2005
- ICRF deficiency causes uncertainties in geodetic positions as much as 10-20 mm for VLBI sites in Southern hemisphere;
- more good radiosources for schedule
- more radiosources
- more VLBI stations with high slew rate 5 deg/sec
- potentially we can reach ~ 1 mm or better by 2010
criteria
Geoscience Australia
17 August 2005
Geoscience
Australia17 August 2005
ICRF instability(wrms vs declination)
Weighted RMS on vs declination
Declination
-90 -60 -30 0 30 60 90
mas
0.0
0.5
1.0
1.5
2.0
Weighted RMS on cos vs declination
Declination
-90 -60 -30 0 30 60 90
mas
0.0
0.2
0.4
0.6
0.8
1.0