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Very-long-baseline interferometric measurements of the positions of planetary orbiters/landers relative to nearby extra galactic radio sources provide information on the positions of the planets in the inertial reference frame described by the measured positions of the radio sources.
The remarkably strong radio gravitational lens PKS 1830-211 consists of a one arcsecond diameter Einstein ring with two bright compact (milliarcsecond) components located on opposite sides of the ring. We have obtained 22GHz VLBA data on this source to determine the intrinsic angular sizes of the compact components.
We describe the design of a radio interferometer composed of a Global Navigation Satellite Systems (GNSS) antenna and a Very Long Baseline Interferometry radio telescope. Our eventual goal is to use this interferometer for geodetic applications including local tie measurements. The GNSS element of the interferometer uses a unique software-defined receiving system and modified commercial geodetic-quality GNSS antenna. We ran three observing sessions in 2022 between a 25 m radio telescope in Fort Davis, Texas (FD-VLBA), a transportable GNSS antenna placed within 100 m, and a GNSS antenna placed at a distance of about 9 km. We have detected a strong interferometric response with a Signal-to-Noise Ratio (SNR) of over 1,000 from Global Positioning System and Galileo satellites. We also observed natural radio sources including Galactic supernova remnants and Active Galactic Nuclei located as far as one gigaparsec, thus extending the range of sources that can be referenced to a GNSS antenna by 18 orders of magnitude. These detections represent the first observations made with a GNSS antenna to radio telescope interferometer. We have developed a novel technique based on a Precise Point Positioning solution of the recorded GNSS signal that allows us to extend integration time at 1.5 GHz to at least 20 min without any noticeable SNR degradation when a rubidium frequency standard is used.
Legacy S/X has been the production system of the IVS since the inception of the service. VGOS was declared operational in 2020 after a visionary journey that involved designing, prototyping, and demonstrating the feasibility of the new observing system to generate high-quality geodetic products. And a fledgling VGOS network of between 8 and 10 stations has been contributing IVS products operationally ever since. That VGOS network had further increased by the end of 2022 to 12 stations, and counting. Currently, the VGOS observing program encompasses the 24-hour VGOS-OPS and VGOS-RD session series; further, a weekdaily VGOS Intensive series has been established (with other VGOS Intensives being set up). In addition to the network, VGOS correlation capabilities have also expanded to try to keep pace with the increased VGOS correlation load, morphing into a multi-center distributed correlator. In this poster, we will provide a status overview of the infrastructure realization efforts of the VGOS station network and the correlation centers as well as plans for a bright VGOS future.
USNO's IERS Rapid Service/Prediction Center (RS/PC) uses the KOKEE12M/WETTZ13S (K2/Ws) baseline for its combination solutions. It would be useful for the RS/PC to be able to use backup baselines in case K2 or Ws is not available. While Ws was undergoing repair in late 2022 through early 2023, ONSA13NE (Oe) replaced Ws to provide immediate UT1 for IVS Analysis Center products but also to begin building a data set for the RS/PC to eventually use to ``characterize'' (assess and approve) the K2/Oe baseline for use in its solutions. The RS/PC needs 60 sessions to be able to characterize a baseline, and the data from the repair period provided 58 sessions, with three additional sessions being observed later. Here we evaluate the K2/Oe baseline to see if it is a viable candidate for submission to the RS/PC for characterization. We evaluate the K2/Oe baseline itself and also compare the K2/Oe baseline to the K2/Ws baseline.