The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) Core Array is a proposed extension of FAST, integrating 24 secondary 40-m antennas implanted within 5 km of the FAST site. This original array design will combine the unprecedented sensitivity of FAST with a high angular resolution (4.3" at a frequency of 1.4 GHz), thereby exceeding the capabilities at similar frequencies of next-generation arrays such as the Square Kilometre Array Phase 1 or the next-generation Very Large Array. This article presents the technical specifications of the FAST Core Array, evaluates its potential relatively to existing radio telescope arrays, and describes its expected scientific prospects. The proposed array will be equipped with technologically advanced backend devices, such as real-time signal processing systems. A phased array feed receiver will be mounted on FAST to improve the survey efficiency of the FAST Core Array, whose broad frequency coverage and large field of view（FOV） will be essential to study transient cosmic phenomena such as fast radio bursts and gravitational wave events, to conduct surveys and resolve structures in neutral hydrogen galaxies, to monitor or detect pulsars, and to investigate exoplanetary systems. Finally, the FAST Core Array can strengthen China's major role in the global radio astronomy community, owing to a wide range of potential scientific applications from cosmology to exoplanet science.

Adaptive optics (AO) is essential for high-quality ground-based observations with large telescopes because it counters the impact of wavefront aberrations caused by atmospheric turbulence. The new vacuum solar telescope（NVST） is one of the most important high-resolution solar observation instruments in the world. Three sets of solar adaptive optics systems have been developed and installed on this telescope: conventional adaptive optics, ground layer adaptive optics, and multi-conjugate adaptive optics. These have been in operation from 2018 to 2023. This paper details the development and application of solar adaptive optics on the NVST and discusses the newest instrumentation.

Aiming at the problem of Radio Frequency Interference (RFI) in the process of radio astronomy observation, the RFI mitigation strategies of domestic and foreign stations are analyzed in detail. According to the RFI problems encountered in the actual observation process of each observatory, the prevention strategies and mitigation methods of RFI are studied from the aspects of active prevention stage, pre-correlation stage, post-correlation stage, machine learning and deep learning. The methods that can be adopted in the active prevention stage, adaptive filtering in the pre-correlation stage, spatial filtering method, VarThreshold, SumThreshold and singular value decomposition in the post correlation stage are systematically analyzed. The applications of principal component analysis based on machine learning, support vector machine, full convolution neural network, convolution neural network, U-Net and other related technologies and methods in RFI signal processing are discussed.

The three-dimensional (3D) Rotating and Lifting Platform (RLP) is the core component of imaging-lidar calibration system for Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO). RLP mainly consists of three parts:the Programmable Logic Controller (PLC), the mechanical, and the standard zero subsystems, is designed to precisely control the beam pointing of the imaging-lidar system. A high-precision digital image processing method is adopted to investigate the performance of RLP. Our results reveal the rotating and lifting positional accuracies are 0.005° and 0.056 mm, respectively, while the corresponding repeatabilities are 0.003° and 0.075 mm, respectively. These outcomes fulfil the experimental requirements for the calibration system. The automatic cruise function of RLP not only minimizes the manual intervention but also improves both the reliability and efficiency for a remote control. The standard zero calibration function enables an effective observation of RLP's positional accuracy and implements a remote calibration in the case of a misalignment. As a result, we accomplish an accurately stable operation for our calibration system over a long period of time.

Based on the introduction of the development of the international SBAS, this paper analyzes the development and service performance of MSAS. It is found that the service area of MSAS can cover the eastern region of China. After describing the MSAS message type and the calculation method of civil aviation user positioning and protection level, the actual service performance in the eastern region of China is evaluated through the actual flight test. The evaluation results show that in eastern China, the positioning accuracy of MSAS is better than that of LPV-250 (16 m horizontally and 20 m vertically); NPA availability and continuity reach 100%; the user protection level meets the integrity requirements. MSAS has effective enhanced positioning and integrity-assurancing capability in eastern China, so that relevant users in the region can use the service according to their own needs; at the same time, MSAS has realized the expansion of service area based on its limited local monitoring stations, which also provides a reference for the expansion of BDSBAS service area and the improvement of service performance in China.