VLBI for Gravity Probe B. IV. A new astrometric analysis technique and a comparison with results from other techniques

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DOIResolve DOI: http://doi.org/10.1088/0067-0049/201/1/4
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TypeArticle
Journal titleAstrophysical Journal, Supplement Series
ISSN0067-0049
Volume201
Issue1
Article number4
AbstractWhen very long baseline interferometry (VLBI) observations are used to determine the position or motion of a radio source relative to reference sources nearby on the sky, the astrometric information is usually obtained via (1) phase-referenced maps or (2) parametric model fits to measured fringe phases or multiband delays. In this paper, we describe a "merged" analysis technique which combines some of the most important advantages of these other two approaches. In particular, our merged technique combines the superior model-correction capabilities of parametric model fits with the ability of phase-referenced maps to yield astrometric measurements of sources that are too weak to be used in parametric model fits. We compare the results from this merged technique with the results from phase-referenced maps and from parametric model fits in the analysis of astrometric VLBI observations of the radio-bright star IMPegasi (HR8703) and the radio source B2252+172 nearby on the sky. In these studies we use central-core components of radio sources 3C454.3 and B2250+194 as our positional references. We obtain astrometric results for IMPeg with our merged technique even when the source is too weak to be used in parametric model fits, and we find that our merged technique yields astrometric results superior to the phase-referenced mapping technique. We used our merged technique to estimate the proper motion and other astrometric parameters of IMPeg in support of the NASA/Stanford Gravity Probe B mission. © 2012. The American Astronomical Society. All rights reserved..
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Herzberg Institute of Astrophysics (HIA-IHA)
Peer reviewedYes
NPARC number21269188
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Record identifier03bc11bf-2b28-4643-9d8b-eed06b872acf
Record created2013-12-12
Record modified2016-05-09
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