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A multi-pixel beamformer using an interferometric array and its application to the localization of newly discovered pulsars




We have developed a multi-pixel beamformer technique, which can be used to enhance the capability of studying pulsars using an interferometric array. Using the Giant Metrewave Radio Telescope (GMRT), we illustrate the application of this efficient technique, which combines the enhanced sensitivity of a coherent array beamformer with the wide field-of-view seen by an incoherent array beamformer. The multi-pixel beamformer algorithm is implemented using the recorded base-band data. With the optimizations in multi-pixelization described in this Letter, it is now possible to form 16 directed beams in real time. We discuss a special application of this technique, where we use continuum imaging followed by the multi-pixel beamformer to obtain the precise locations of newly discovered millisecond pulsars with the GMRT. Accurate positions measured with single observations enable highly sensitive follow-up studies using a coherent array beamformer and rapid follow-up at higher radio frequencies and other wavelengths. Normally, such accurate positions can only be obtained from a long-term pulsar timing programme. The multi-pixel beamformer technique can also be used for highly sensitive targeted pulsar searches in extended supernova remnants. In addition this method can provide optimal performance for large-scale pulsar surveys using multi-element arrays.