Results 11 to 20 of about 21,511,845 (71)

Source structure effects in VLBI Global Observing System (VGOS) observations

, 2022
VLBI Global Observing System (VGOS) is now regularly observing to produce the best geodetic VLBI data ever, with a thermal noise level of about 3 ps. However, the systematic errors due to angular structure of the radio sources are becoming prominent in these high-precision VGOS observations.
Ming Hui Xu, Tuomas Savolainen, Robert Heinkelmann, Harald Schuh   +3 more
openaire   +3 more sources

Impacts of the image alignment over frequency for VLBI Global Observing System [PDF]

, 2021
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).
Xu, Ming H., Anderson, James M, Harald Schuh, Schuh, Harald, Tuomas Savolainen, Nataliya Zubko, Xu, Ming H, Kareinen, Niko, Savolainen, Tuomas, Zubko, Nataliya, James M. Anderson, Susanne Lunz, Niko Kareinen, Anderson, James M., Lunz, Susanne, Ming H. Xu   +15 more
core   +1 more source

Baseline Vector Repeatability at the Sub‐Millimeter Level Enabled by Radio Interferometer Phase Delays of Intra‐Site Baselines

Journal of Geophysical Research: Solid Earth, Volume 128, Issue 3, March 2023., 2023
Abstract We report the results of position ties for short baselines at eight geodetic sites based on phase delays that are extracted from global geodetic very‐long‐baseline interferometry (VLBI) observations rather than dedicated short‐baseline experiments.
Ming H. Xu, Tuomas Savolainen, Sergei Bolotin, Simone Bernhart, Christian Plötz, Rüdiger Haas, Eskil Varenius, Guangli Wang, Jamie McCallum, Robert Heinkelmann, Susanne Lunz, Harald Schuh, Nataliya Zubko, Niko Kareinen   +13 more
wiley   +1 more source

Impact of Tropospheric Ties on UT1‐UTC in GNSS and VLBI Integrated Solution of Intensive Sessions

Journal of Geophysical Research: Solid Earth, Volume 127, Issue 11, November 2022., 2022
Abstract Very Long Baseline Interferometry (VLBI) intensive (INT) sessions are critical for the rapid determination and densification of Universal Time 1‐Coordinate Universal Time (UT1‐UTC), which plays an important role in satellite geodesy and space exploration missions and is not predictable over longer time scales.
Jungang Wang, Maorong Ge, Susanne Glaser, Kyriakos Balidakis, Robert Heinkelmann, Harald Schuh   +5 more
wiley   +1 more source

Measuring the Deflection of the Vertical via Local Reference Point Surveying and Pointing Calibration of a VLBI Telescope: A Case Study at the Urumqi Station

Earth and Space Science, Volume 8, Issue 10, October 2021., 2021
Abstract According to Newton's law of universal gravitation, the movement of matter and the change in density cause a gravitational variation. Due to the anisotropic distribution of matter, the vertical and the normal directions at a point on the ground are probably inconsistent, which is referred to as the deflection of the vertical (DOV) and is ...
Zhibin Zhang, Xiaohui Ma, Zhongmiao Sun, Ali Zhang, Ye Yuan, Zhengxiong Sun   +5 more
wiley   +1 more source

The Role of Spatial Gradient on Vertical Total Electron Content Extraction From Geodetic Very Long Baseline Interferometry Observation: Case Study CONT08 to CONT17‐L1

Space Weather, Volume 19, Issue 6, June 2021., 2021
Abstract Geodetic very long baseline interferometry (VLBI) observations are carried out, with the legacy system, using two well‐separated frequency bands in order to determine first‐order ionospheric delay corrections corresponding to the combined effect of total electron content (TEC) at two stations forming a baseline.
Hossein Etemadfard, Robert Heinkelmann, Masoud Mashhadi Hossainali, Harald Schuh   +3 more
wiley   +1 more source

Imaging VGOS Observations and Investigating Source Structure Effects

Journal of Geophysical Research: Solid Earth, Volume 126, Issue 4, April 2021., 2021
Abstract The next‐generation, broadband geodetic very long baseline interferometry system, named VGOS, is being developed globally with an aim to achieve 1 mm accuracy for station positions. Currently, the systematic errors in VGOS broadband delays are still about 20 ps.
Ming H. Xu, Tuomas Savolainen, Nataliya Zubko, Markku Poutanen, Susanne Lunz, Harald Schuh, Guang L. Wang   +6 more
wiley   +1 more source

The Vienna VLBI raw data simulator and correlator in the VGOS era [PDF]

, 2022
Die Very Long Baseline Interferometry (VLBI) ist ein Verfahren, bei der weltweit verteilte Radioteleskope eingesetzt werden, um die elektromagnetischen Feldstärken von natürlichen Radiosignalen von kosmischen Quellen zu messen.
Gruber, Jakob Franz; orcid:
core   +1 more source

Impact of the image alignment over frequency for the VLBI Global Observing System

, 2022
Aims. The VLBI Global Observing System (VGOS), which is the next generation of geodetic very long baseline interferometry (VLBI), observes simultaneously in four frequency bands in the range 3.0-10.7 GHz (expected to be extended to 14 GHz).
Xu, Ming H., Kareinen, Niko, Savolainen, Tuomas, Zubko, Nataliya, Schuh, Harald, Anderson, James M., Lunz, Susanne   +6 more
core   +1 more source

Prospective study of high geodetic resolution to future VGOS reference point determination

Geodesy and Geodynamics, 2019
The fast slewing rate and wide band of the VLBI2010 Global Observing System (VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points (RPs) of high precisions.
Zhibin Zhang, Guangli Wang, Dezhen Xu, Shize Song   +3 more
doaj   +1 more source