Progress in VLBI observations with the Haoping 40 m Radio Telescope at the National Time Service Center

The Haoping 40 m radio telescope at the National Time Service Center was built in 2014 and is primarily used to observe navigation satellites and pulsars. Since the first successful very long baseline interferometry observation of L-band radio source fringes in 2022, ten observations have been made so far. The stations involved in the observations include the Haoping 40 m radio telescope (Haoping), the Tianma 65 m radio telescope (Tianma), the Nanshan 26 m radio telescope (Urumqi), the Guizhou 500 m radio telescope (FAST), the Jilin 13 m radio telescope (Jilin), the Effelsberg 100 m radio telescope (Effelsberg), the Onsala 25 m radio telescope (Onsala), and the Chiang Mai 40 m radio telescope (Chiang Mai). This paper presents details on the specifications of the Haoping 40 m radio telescope, as well as the design of the very long baseline interferometry experiment, the observation process, and the data processing. We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope, using Distributed FX Correlator to obtain excellent results. We confirm that the telescope is capable of participating in very long baseline interferometry observations and performing specific data processing tasks. It can therefore play a greater role in future very long baseline interferometry observations.