出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We are carrying out a simulation study to characterise the advantages of VLBI with multiple beams, which will be a feature of the next generation of instruments. We will focus on VLBI astrometric measurements at lower frequencies (1.4 GHz and below). For our simulations, we have selected a network consisting of ASKAP, the Australian SKA precursor, plus existing Australian antennas from the LBA (Long Baseline Array) and the new antenna in New Zealand (figure 1a). We have used different models to represent the ionospheric turbulences and frequencies. The preliminary results show an improvement of an order of magnitude in the astrometric precision achieved using multiple calibrators with angular separations of a few degrees around the target, with respect to a single nearby (1◦ away) calibrator. Such astrometric precision is comparable to using in-beam phase referencing with a calibrator some arcminutes away. We plan to expand our simulations to include other networks with multi-beam capability, and ultimately SKA-like configurations.
