Self-calibration strategy for a LOFAR solar radio burst observation

The LOw Frequency ARray (LOFAR) is a novel radio interferometer consisting of a central core near Exloo in the Netherlands, remote stations in the Netherlands, and international stations. It observes in two frequency bands, the low band of 10-90 MHz and the high band of 110-250 MHz. The key science project "Solar Physics and Space Weather with LOFAR" aims at studying the solar activity and its influence on interplanetary space. Solar radio radiation in the low and high band emanates from the upper and middle corona, respectively. We present early commissioning observations of the Sun, that serendipitously include a weak radio burst. Since no external calibrator was observed, a self-calibration approach has to be used. This works well for the quiet Sun, but not for the burst data. We develop a self-calibration strategy for radio bursts, and discuss the general properties of such a self-calibration method. Our results lead to the conclusion that external calibrators with known source structure should generally be preferred. (C) 2016 WILEY-VCH Verlag GmbH&Co. KGaA, Weinheim