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Sphero-Conical Modeling for the Estimation of Very Long Baseline Interferometry Invariant Point [PDF]

open access: yesSensors, 2022
A geodetic reference frame is a fundamental element in geoinformation fields such as autonomous navigation and digital twins. The international terrestrial reference frame is established and maintained using several space-geodetic techniques, including ...
Tae-Suk Bae, Chang-Ki Hong
doaj   +2 more sources

The Transformational Power of Frequency Phase Transfer Methods for ngEHT

open access: yesGalaxies, 2023
(Sub) mm VLBI observations are strongly hindered by limited sensitivity, with the fast tropospheric fluctuations being the dominant culprit. We predict great benefits from applying next-generation frequency phase transfer calibration techniques for the ...
María J. Rioja   +2 more
doaj   +1 more source

Three-dimensional Orbit of AC Her Determined: Binary-induced Truncation Cannot Explain the Large Cavity in This Post-AGB Transition Disk

open access: yesThe Astrophysical Journal, 2023
Some evolved binaries, namely post–asymptotic giant branch (AGB) binaries, are surrounded by stable and massive circumbinary disks similar to protoplanetary disks found around young stars. Around 10% of these disks are transition disks: they have a large
Narsireddy Anugu   +19 more
doaj   +1 more source

VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B

open access: yesThe Astrophysical Journal, 2023
Tension remains between the observed and modeled properties of substellar objects, but objects in binary orbits, with known dynamical masses, can provide a way forward.
William O. Balmer   +100 more
doaj   +1 more source

A New Very Long Baseline Interferometry Method Based on the Uplink Signal

open access: yesIEEE Access, 2020
Very long baseline interferometry (VLBI) is widely used for astronomical observations and navigation of deep space receivers. To solve the problems of the downlink signal being excessively weak to be received and the excessively large acquisition time, a
Linshan Xue, Weiren Wu, Xue Li
doaj   +1 more source

Selective Dynamical Imaging of Interferometric Data

open access: yesThe Astrophysical Journal Letters, 2022
Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky.
Joseph Farah   +234 more
doaj   +1 more source

High-sensitivity Beamformed Observations of the Crab Pulsar's Radio Emission

open access: yesThe Astrophysical Journal, 2023
We analyzed four epochs of beamformed European VLBI Network data of the Crab Pulsar at 1658.49 MHz. With the high sensitivity resulting from resolving out the Crab Nebula, we are able to detect even the faint high-frequency components in the folded ...
Rebecca Lin, Marten H. van Kerkwijk
doaj   +1 more source

Observational Evidence of a Centi-parsec Supermassive Black Hole Binary Existing in the Nearby Galaxy M81

open access: yesThe Astrophysical Journal, 2023
Studying a centi-parsec supermassive black hole binary (SMBHB) would allow us to explore a new parameter space in active galactic nuclei, and these objects are also potential sources of gravitational waves.
Wu Jiang   +8 more
doaj   +1 more source

ALMA High-frequency Long-baseline Campaign in 2019: Band 9 and 10 In-band and Band-to-band Observations Using ALMA’s Longest Baselines

open access: yesThe Astrophysical Journal Supplement Series, 2023
The Atacama Large Millimeter/submillimeter Array high-frequency long-baseline campaign in 2019 (HF-LBC-2019) was arranged to undertake band 9 (690 GHz) and 10 (850 GHz) observations using the longest 16 km baselines in order to explore calibration ...
Luke T. Maud   +8 more
doaj   +1 more source

Inverse MultiView. II. Microarcsecond Trigonometric Parallaxes for Southern Hemisphere 6.7 GHz Methanol Masers G232.62+00.99 and G323.74–00.26

open access: yesThe Astrophysical Journal, 2023
We present the first results from the Southern Hemisphere Parallax Interferometric Radio Astrometry Legacy Survey: 10 μ as accurate parallaxes and proper motions for two Southern Hemisphere 6.7 GHz methanol masers obtained using the inverse MultiView ...
L. J. Hyland   +13 more
doaj   +1 more source

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