Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes

Details Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes

Aug 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010jgeod..84..515a&link_type=abstract

Journal of Geodesy, Volume 84, Issue 8, pp.515-525

Statistics

Computation

1

Vlbi, Signal Path Variation, Gravitational Deformation, Illumination Function, Radio Telescope

Scientific paper

This paper sets the rules for an optimal definition of precise signal path variation (SPV) models, revising and highlighting the deficiencies in the calculations adopted in previous studies and improving the computational approach. Hence, the linear coefficients that define the SPV model are rigorously determined. The equations that are presented depend on the dimensions and the focal lengths of the telescopes as well as on the feed illumination taper. They hold for any primary focus or Cassegrainian very long baseline interferometry (VLBI) telescope. Earlier investigations usually determined the SPV models assuming a uniform illumination of the telescope mirrors. We prove this hypothesis to be over-simplistic by comparing results derived adopting (a) uniform, (b) Gaussian and (c) binomial illumination functions. Numerical computations are developed for AZ-EL mount, 32 m Medicina and Noto (Italy) VLBI telescopes, these latter being the only telescopes which possess thorough information on gravity-dependent deformation patterns. Particularly, assuming a Gaussian illumination function, the SPV in primary focus over the elevation range [0°, 90°] is 10.1 and 7.2 mm, for Medicina and Noto, respectively. With uniform illumination function the maximal path variation for Medicina is 17.6 and 12.7 mm for Noto, thus highlighting the strong dependency on the choice of the illumination function. According to our findings, a revised SPV model is released for Medicina and a model for Noto is presented here for the first time. Currently, no other VLBI telescope possesses SPV models capable of correcting gravity-dependent observation biases.

Affiliated with

Also associated with

No associations

Rating

Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effects of illumination functions on the computation of gravity-dependent signal path variation models in primary focus and Cassegrainian VLBI telescopes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-981353