6533b854fe1ef96bd12ae838
RESEARCH PRODUCT
High Precision Astrometry Over Large Angular Scales with Closure Constraints: The Triplet 1803+784/1928+738/2007+777
Irwin I. ShapiroEduardo RosThomas P. KrichbaumJ. M. MarcaideJ. C. GuiradoRobert A. PrestonM. I. RatnerA. Witzelsubject
Constraint (information theory)PhysicsAngular distanceSkymedia_common.quotation_subjectVery-long-baseline interferometryClosure (topology)Phase (waves)ObservableAstrophysicsAstrometrymedia_commondescription
The technique of differential astrometry using the phase-delay VLBI observable promises fractional precisions of ~2 × 10−9 in the determination of the separation of sources 5° or 6° apart on the sky (Guirado et al. 1995a; Lara et al. 1996). In our present research we seek further improvement in this technique through using triplets of radio sources, which provide a closure constraint in the determination of relative angular positions. This constraint not only eases the resolution of the phase-cycle ambiguities (a major problem in the least-squares approach to astrometry with phase delays), but it also strongly constrains the space of allowable parameter values.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1996-01-01 |