Speaker
Description
The LOw Frequency Array (LOFAR) is a hierarchical array of dipole and bowtie antennas, distributed across Europe. The Irish LOFAR station (IE613) is located at Birr Castle, Co. Offaly. As one of the 14 international stations, it comprises a set of Low Band Antennas (LBA) and 96 High Band Antennas (HBA) tiles. The response of a single station is trivial and different works have been carried out in the past. Several factors contribute to the overall performance of the system, among them the effective collecting area, beam model, contamination due to radio frequency interferences (RFI), system noise and turbulent effects in the ionosphere (e.g. Kondratiev et al., 2016 ). As a ’software telescope’, LOFAR is particularly sensitive to signal corruption from both direction-independent and direction-dependent effects, which influence the observed radio waves as they travel from the source to the observer. In this regard, Radio Interferometer Measurement Equation (RIME), as extension of the fundamental van Cittert-zernike theorem, is employed in data calibration (e.g. Kansabanik et al., 2025, Creaner & Carozzi, 2019, Murley et a;., 2019, Price & Smirnov, 2015, Tasse et al., 2012, Smirnov et al. (I),(II),(III),(IV), 2011, Nijboer & Noordam, 2007, Sault et al., 1996 ). This mathematical framework implements correction factors in form of elements of Jones 2x2 matrices (or Mueller 4x4 matrices). Taking into account its complexity, the response of individual LOFAR stations has been extensively studied (e.g. McKenna et al., 2024, Blaszkiewicz et al., 2018, Kondratiev et al., 2016, Bilous et al., 2016, Noustsos et al., 2015 ). In this study, we present an analysis of the HBA response of the Irish station (IE613) by tracking 11 pulsars across the sky. We investigate how the signal-to-noise ratio (S/N) varies as each pulsar rises, culminates, and sets, thereby constructing a sensitivity map of the station’s beam pattern.
