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Our paper, "Reducing Radio Occultation Uncertainty Using High-Rate GNSS Satellite Clock Estimation," was accepted by Measurement Science and Technology (Impact Factor: 3.4) on November 24, 2025.
Upon the invitation of the Department of Earth Sciences and Engineering at Missouri University of Science and Technology, Dr. Jian Yao gave a seminar presentation titled "Precise Positioning, Navigation, and Timing" on October 15, 2025.
Dr. Jian Yao taught a five-day professional training course on Satellite Geodesy to a U.S. government agency, September 22-26, 2025.
Upon the recommendation of Dr. Michael Coleman and Allison Craddock, Dr. Jian Yao attended the Consultative Committee for Time and Frequency (CCTF) meeting at the International Bureau of Weights and Measures (BIPM) in Paris, France, September 18-19, 2025, as the International GNSS Service (IGS) representative. The CCTF meeting is a high-level, invitation-only meeting in the field of timekeeping. Dr. Yao delivered a presentation titled Report from the International GNSS Service.
Dr. Jian Yao and Faisal Wahabu attended the Institute of Navigation (ION) GNSS+ Meeting in Baltimore, Maryland, September 9-12, 2025. Their peer-reviewed conference paper, titled An Algorithm for Estimating Thermospheric Density Using LEO Dual-Frequency GNSS Receivers Design, Uncertainty Analysis, and Validation, is available here. This work is a collaboration among SLU, Vector Space, and Atmospheric and Environmental Research (AER), with metadata provided by the University Corporation for Atmospheric Research (UCAR).
Since July 2025, Dr. Jian Yao has been serving as a Guest Editor for the special issue titled “GNSS Beyond Positioning and Navigation” in IOP Measurement Science and Technology. Researchers whose work falls within the scope of this issue are invited to submit a manuscript.
Dr. Jian Yao attended the GEOINT Symposium and the SLU Geospatial Retreat in May 2025.
Our group member, Jace Smuszkiewicz, presented his poster titled "New SLU GNSS Receivers and Their Application Towards Storm Monitoring" at Saint Louis University School of Science and Engineering (SLU SSE) Undergraduate Research Showcase on April 30, 2025. He has been offered the 2025 summer internship position at Masterclock, Inc.
Dr. Jan-Peter Weiss and Dr. Ming Li from the University Corporation for Atmospheric Research (UCAR) gave a course presentation titled "Global Navigation Satellite System (GNSS) Remote Sensing of the Earth's Atmosphere, Ionosphere, and Surface" on April 29, 2025. Dr. Weiss serves as the Director of the UCAR COSMIC Program and Dr. Li is a Project Scientist. They also introduced student internship opportunities at UCAR.
Dr. Demetrios Matsakis visited Saint Louis University on March 21, 2025, where he delivered an invited presentation titled "Modern Timekeeping: How and Why" to faculty members and students from the Department of Earth, Environmental, and Geospatial Sciences (EEGS), as well as the School of Science and Engineering. Born in St. Louis, Dr. Matsakis earned his PhD in Physics from UC Berkeley under Nobel Laureate Charles Townes, the inventor of the maser and laser. He spent over 40 years at the U.S. Naval Observatory, working on almost every aspect of modern timekeeping—from building atomic clocks to leading the Time Department for nearly two decades, and even negotiating in Geneva. Since retiring, he has continued his work with Masterclock, Inc.
Dr. Jian Yao was elected Vice Chair of the IGS (International GNSS Service) Clock Products Working Group (CPWG) on February 5, 2025. Thank you to the IGS CPWG for the opportunity to contribute.
Dr. Jian Yao presented on "GPS Clock Products for NGS" at the Institute of Navigation (ION) ITM & PTTI Meeting on January 29, 2025. He also served as a Session Chair during the meeting.
Dr. Jian Yao has been serving on National Science Foundation (NSF) proposal panels since December 2024.
We received three packages of GNSS devices from NOAA's National Geodetic Survey (NGS) on November 13, 2024. We plan to establish a GNSS station equipped with atomic clocks at SLU, to study the impact of atomic clocks on the GNSS infrastructure. Thank you NGS for the support.
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