Fast Searches for Astronomical Transients Based on Focal-Field Feature Matching

Since fast transients such as fast radio bursts are short-duration events, the telescope should require a wide instantaneous field of view (FoV). Unlike the traditional beam-scanning technology, this letter proposes a new approach for transient radio target detection using focal-field feature matching. Based on the off-axis focusing characteristics of the parabolic antenna reflector, the focal-field distribution (FFD) database is established on the basis of various incident angles and frequencies. Combining the frequency feature of the transients, an improved compressed sensing method using the multiple-frequency joint estimation is proposed. The direction of the transients can be identified through the relationship of the reconstructed index and FFD feature database. Moreover, according to the received energy distribution, a database-selection method is proposed as a preprocessing to reduce the algorithm complexity. A simplified antenna model is used to generate the FFD database. The simulation results demonstrate that this approach can accurately estimate the transient position. In addition, compared with the traditional multibeam scanning system, the proposed method increases the FoV of the radio telescope and can provide an extended detection for transients.