In a study published in The Astronomical Journal, ZHANG Yigong and Prof. WANG Jiancheng from Yunnan Observatories of the Chinese Academy of Sciences, and their collaborators, proposed a new method to improve the precision of astrometric observation for near-Earth objects (NEOs).

The precise astrometric observation of small NEOs is an important research topic in the astrometric discipline which can promotes multidisciplinary research in the fields such as the origin and evolution of the solar system, the detection and early warning of small NEOs, and deep-space navigation.

Incidents of small NEOs hitting the earth have occurred frequently. In recent years, the international community has paid more attention to the monitoring and early warning of small NEOs, and China is also actively developing a near-Earth object defense system. Long-period and multi-epoch astrometric observations of small near-Earth objects are helpful to monitor the orbit of these targets in order to prevent potential risks.

The characteristics of small NEOs such as faintness and fast moving speed restrict the accuracy and precision of their astrometric observations. In order to reduce the impact of these factors, the researchers in this study propose a new method.

The images of background stars and moving objects in the obtained observation data set were segmented into two independent data sets, and then the “shift-and-stack” method was used for the background stars and moving objects, respectively. 

The researchers performed image fusion for the superimposed image sets according to the observation time. A high-quality image set can be obtained, which contains many background stars and moving objects with high signal-to-noise ratios (S/Ns), and the saturation of brighter background stars can be avoided. 

Besides, they performed astrometric reduction on the image data of small near-Earth object observed by 1 m optical telescope of Yunnan Observatories. The results showed that this new method can significantly improve the accuracy and precision of astrometry.

Based on the measured data at the observation station, the researchers also proposed a specific method for establishing observable limiting apparent magnitude (OLAM) of moving objects, and an observation strategy for the moving targets.