Fig. 1. Schematic diagram of relationship between standard coordinates of a star and its profile in focal plate of telescope

Fig. 2. Schematic diagram of inserting nodes into red and black tree (RB-Tree)

Fig. 3. An example of RB-Tree search and traversal in this work

Fig. 4. Schematic diagram of GeoHash encoding and matching method for stars proposed in this work

Fig. 5. An example of GeoHash encoding and matching of navigation stars

Fig. 6. A photo of Dragonfly Telescope

Fig. 7. An image (32 MB) taken by Dragonfly Telescope. Initial central view shown in box

Fig. 8. Range of matched points by polynomial fitting varies with fitting order. (a) Linear and 2-order fitting areas; (b) 2-order and 3-order fitting areas; (c) 3-order and 4-order fitting areas

Fig. 9. Plate constants from polynomial fitting in star pattern matching, in which constants in one shade have the same order. (a), (c) Results of 3-order polynomial fitting; (b), (d) results of 4-order polynomial fitting

Fig. 10. Deviation of space objects’ positioning results compared to those of system built-in software in wide-field images. (a) In Ra direction; (b) in Dec direction

Fig. 11. Schematic diagram of telescope pointing for star pattern matching test, in which celestial sphere represented by a unit sphere

Fig. 12. Positioning results of satellites tracked by laser ranging (SLR) used for orbital correlation in various observation locations of wide-field images. Values in brackets represent average correlation differences in Ra and Dec, respectively, and numbers of frames in each observation are shown after @. (a) Result comparison of multiple objects in less passes; (b) result comparison of two objects in multiple passes

Fig. 13. Comparing root mean square (RMS) values of SLR positioning in wide-field images between proposed method and system built-in software. (a) In Ra direction; (b) in Dec direction