Impact of the image alignment over frequency for the VLBI Global Observing System
| Autor: | Ming H. Xu, Tuomas Savolainen, James M. Anderson, Niko Kareinen, Nataliya Zubko, Susanne Lunz, Harald Schuh |
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| Přispěvatelé: | Sciences, EDP, Maanmittauslaitos, National Land Survey of Finland, Anne Lähteenmäki Group, Department of Electronics and Nanoengineering, Technische Universität Berlin, Finnish Geospatial Research Institute, Deutsches GeoForschungsZentrum, Aalto-yliopisto, Aalto University |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
radio continuum: galaxies
galaxies: active jets [galaxies] FOS: Physical sciences Astronomy and Astrophysics galaxies: jets Astrophysics - Astrophysics of Galaxies galaxies [radio continuum] Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) active [galaxies] astrometry ddc:520 reference systems |
| Zdroj: | Astronomy and Astrophysics |
| Popis: | The VLBI Global Observing System, which is the next generation of geodetic VLBI and is called VGOS, observes simultaneously at four frequency bands in the range 3.0--10.7 GHz (expected to be extended to 14 GHz). Because source structure changes with frequency, we aim to study the source position estimates from the observations of this new VLBI system. Based on an ideal point source model, simulations are made to determine the relation between the source positions as determined by VGOS observations and the locations of the radio emission at the four bands. We obtained the source positions as determined by VGOS observations as a function of the source positions at the four frequency bands for both group and phase delays. The results reveal that if the location of the radio emission at one band is offset with respect to that at the other bands, the position estimate can be shifted to the opposite direction and even by more than three times that offset. The VGOS source positions will be very variable with time and very imprecise in the sense of relating to the locations of the radio emission at the four bands, if the effects of source structure are not modeled. The image alignment over frequency is essential in order to model the effects of source structure in VGOS observations, which is the only way to mitigate these strong frequency-dependent impacts on VGOS source positions. Comment: 10 pages, 4 figures, submitted to A&A |
| Databáze: | OpenAIRE |
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