Department of Physics & Astronomy
University of New Mexico

Center for Astrophysics Research and Technologies Seminar Series

Single-band absolute astrometry: mitigation of the ionospheric contribution

Presented by Leonid Petrov (NASA)

Radio measurements can provide absolute astrometry with high precision allowing for parallax distances within our Milky Way Galaxy and the establishment of a celestial reference frame. The ionospheric contribution affects path delay. When simultaneous dual-band observations are used for absolute astrometry, the residual unaccounted contribution of the ionosphere is at a level of several picoseconds. But there are two cases when we need to process single band group delays: a) some observations provided usable data only for one band; b) an entire experiment used only one band. A common approach is to utilize Global Navigation Satellite System (GNSS) Total Electron Content (TEC) maps for computing the contribution of the ionosphere to group and phase delays. I made an attempt to account rigorously for remaining ionosphere-related errors and their impact on source position estimates. This is achieved by developing an empirical stochastic model, applying fudge factors, and applying a de-bias model. The goal is to get the best solutions for these two cases and provide realistic estimates of residual errors.

2:00 pm, Thursday, September 8, 2022

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