Application of attributables to the correlation of surveillance radar measurements.

Space surveillance by radar is especially used for the low Earth orbit to maintain a database, also calledcatalogue, of objects on orbit. Among others, surveillance radars which are constantly scanning a region ofinterest in the sky are used for this purpose. The detections from such a radar which cannot be assigned toan already known catalogue object might not contain enough information to obtain a reliable initial orbitfor a new catalogue entry from a single measured pass, also called tracklet. Instead, two tracklets can becombined to improve the quality of the initial orbit which leads to the correlation problem. This means thatit has to be tested whether two tracklets belong to the same object and an initial orbit has to be derivedby combining the tracklets. A common approach to condense the information in the tracklet is fitting themwith so-called attributables. Because radar observations include different types of observables, the fitting ofthese attributables has to be considered as an important part of the entire correlation process. This paperanalyses the effect of the attributable fitting considering the achieved accuracy and influence on the trackletcorrelation. A new singularity-free coordinate system is introduced, which improves the results of the fittingand correlation. Finally, a test on a simulated survey scenario introduces two additional filters to remove falsepositive correlations. It is shown that the attributable-based approach can be applied successfully to trackletsof up to three minutes length with different detection frequencie