A Comparison of Radio and Optical Astrometric Reduction Algorithms [report]

G. H. Kaplan
1998 unpublished
This paper examines the correspondence between two approaches to astrometric observational reductions: the approach based on angular observables used for optical observations, and the approach based on the interferometric delay observable used for very long baseline radio interferometry (VLBI) observations. Specifically, of interest here is the group of algorithms that have become standard in accounting for the physical effects traditionally called annual and diurnal aberration and
more » ... light bending. These algorithms are important because they must be applied to all wide-angle astrometric measurements, whether ground-or space-based, and regardless of the distance of the objects observed. A procedure is presented by which VLBI algorithms can be used for optical observations. This scheme can help to guarantee consistent treatment of observational results in the two regimes. It also allows for the evaluation of the precision of the algorithms. Differences between angle-based and delay-based algorithms in current use are shown to be less than 1 microarcsecond. However, the physical models used as the bases for the algorithms must be improved to reach external accuracies at such levels. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. UU 18. NUMBER OF PAGES 15 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18
doi:10.21236/ada423227 fatcat:2zy7f6hkxfdcpgs5wdko2fjyoy