arXiv subjects

Yuan-wei Wu

Publications and source records attributed to Yuan-wei Wu.

3 recordsLinked to original sources

arXiv2026

Accuracy Analysis of VLBI Universal Time Measurement Based on a GNSS Single-Station Regional Ionospheric Model

Universal Time (UT1) is a key parameter characterizing Earth's rotation, and very long baseline interferometry (VLBI) is the mainstream technique for measuring UT1. To address the limitations in the timeliness and accuracy of existing global ionospheric models for single-frequency VLBI UT1 measurements, we construct a single-station regional ionospheric model using GNSS data from the VLBI stations on the Jilin-Kashi baseline. We apply this model to VLBI observations and compare its correction performance with that of a global predictive model and a global post-processed model. The results show that the line-of-sight ionospheric delays and baseline corrections calculated with the single-station regional model have precision close to that of the global post-processed model and are substantially better than those of the global predictive model. After correction with the single-station regional model, the derived UT1 values differ from the US Naval Observatory (USNO) reference values by a mean bias of -15.6 us and an RMS deviation of 82.3 us, both better than the results obtained with the other two model classes. A single-station regional ionospheric model constructed independently from GNSS data available at VLBI stations can effectively correct single-frequency VLBI observations and support quasi-real-time high-precision UT1 measurements. It therefore has important value for improving the timeliness of independent UT1 products.

astro-ph.EP↗

arXiv2026

GASV: A New VLBI analysis software for Geodesy and Astrometry

We present GASV, a novel Python-based software package specifically designed for the analysis of Very Long Baseline Interferometry (VLBI) data. Developed with ease of installation and user friendliness in mind, GASV supports both pipeline and interactive processing modes. The software processes VLBI baseline delays and rates in standard formats such as HOPS outputs and NGS card files to estimate key geodetic and astrometric parameters, including station coordinates, Earth Orientation Parameters, source coordinates, clock parameters, and atmospheric models. We evaluate the capabilities and performance of GASV, demonstrating that its parameter estimation accuracy for IVS INT, Regular, and CONT sessions is comparable to that achieved by the VLBI analysis centers at BKG and USNO. As a state-of-the-art tool, GASV not only enables high-quality single-session data processing but also but also supports global analyses of long-term SINEX files, generating Celestial Reference Frame and Terrestrial Reference Frame solutions with reliable accuracy.

astro-ph.IM↗

arXiv2019

Assessing the Performance of Molecular Gas Clump Identification Algorithms

The detection of clumps(cores) in molecular clouds is an important issue in sub-millimetre astronomy. However, the completeness of the identification and the accuracy of the returned parameters of the automated clump identification algorithms are still not clear by now. In this work, we test the performance and bias of the GaussClumps, ClumpFind, Fellwalker, Reinhold, and Dendrograms algorithms in identifying simulated clumps. By designing the simulated clumps with various sizes, peak brightness, and crowdedness, we investigate the characteristics of the algorithms and their performance. In the aspect of detection completeness, Fellwalker, Dendrograms, and Gaussclumps are the first, second, and third best algorithms, respectively. The numbers of correct identifications of the six algorithms gradually increase as the size and SNR of the simulated clumps increase and they decrease as the crowdedness increases. In the aspect of the accuracy of retrieved parameters, Fellwalker and Dendrograms exhibit better performance than the other algorithms. The average deviations in clump parameters for all algorithms gradually increase as the size and SNR of clumps increase. Most of the algorithms except Fellwalker exhibit significant deviation in extracting the total flux of clumps. Taken altogether, Fellwalker, Gaussclumps, and Dendrograms exhibit the best performance in detection completeness and extracting parameters. The deviation in virial parameter for the six algorithms is relatively low. When applying the six algorithms to the clump identification for the Rosette molecular cloud, ClumpFind1994, ClumpFind2006, Gaussclumps, Fellwalker, and Reinhold exhibit performance that is consistent with the results from the simulated test.

astro-ph.GA↗