NASA GSFC global VLBI quarterly solutions
NASA Goddard Space Flight Center provides solutions using all
publicly accessible Very Long Baseline Interferometry (VLBI) data accumulated
since 1980.04.11
through 2025.06.03
on a quarterly basis. The data used in these solutions are available
from the NASA Crustal Dynamics Data Information System
(CDDIS).
There are four types of solutions:
- Geodetic global solutions present estimates of stations
positions, station velocities, harmonic variations in site
positions, parameters of non-linear station motions, positions
of extragalactic radio sources, and the estimates of an
expansion of the Earth orientation parameters into harmonic
and B-spline bases from analysis of
20,157,635
VLBI group delays derived from processing
20,595
geodetic experiments.
The results from NASA GSFC geodetic global VLBI solutions
are available here: gsf.
- Geodetic baseline solutions that present estimates
of baseline lengths between radio telescopes adjusted using least
squares in analysis of VLBI group delays derived during analysis of
20,157,635
VLBI group delays accumulated
since 1980.04.11
through 2025.06.03
derived from processing
20,595
geodetic experiments. Baseline lengths are invariant
with respect to a group of rotations and translations, and therefore,
unlike to station positions, are determined uniquely from observations.
The results from NASA GSFC geodetic baseline VLBI solutions
are available here: bas.
- Geodetic solutions for UT1 that present estimates of the Earth
rotation parameter UT1 from analysis of
496,659
VLBI group delays accumulated
since 1990.01.03
through 2025.06.03
derived from processing
12,650
1-hr Intensive VLBI geodetic experiments.
The results from NASA GSFC geodetic solutions for UT1
are available here: int.
- Astrometric solutions that present positions of compact radio sources
and estimates of other parameters using all available VLBI observations,
in total 27,575,625
delays,
at 8.6 GHz and 2.2 GHz, as well at 5 and 22 GHz from
1187
astrometric experiments from
74
dedicated absolute astrometry programs, as well as
routine geodetic experiments accumulated since
1980.04.11
through 2025.06.03
.
The results from NASA GSFC astrometric VLBI solutions are available here:
rfc.
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Last update: 2025.06.30_20:33:11
UTC