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Ionospheric impact and calibration for LOFAR (Invited)

Author: Ilse van Bemmel


Co-Authors: Ger de Bruyn (ASTRON); Mark Aartsen (Univ of Adelaide); John McKean (ASTRON); Ronald Nijboer (ASTRON); Huib Intema (NRAO); Maaike Mevius (KVI); Bas van der Tol (Leiden Observatory); Stefan Wijnholds (ASTRON); Jan Noordam (ASTRON)

Session: INS4: LOFAR, the LOw Frequency ARray: Ongoing Developments and Early Results

Presentation type: Talk      10:57  Thursday 29th 10:00-11:15 


LOFAR is rapidly picking up speed and producing magnificent first results in many fields. In this process we are learning new things about aperture array systems every day. LOFAR requires a new approach to calibration, if we want to optimize the use of its broad continuous frequency coverage and large field of view. A significant problem in calibration is the Earth's ionosphere. Due to small changes in ionospheric electron density, radio sources appear to move and distort. This affects the ability to make very deep observations, which require hours or even days of observing time. In order to optimize the science return from LOFAR, we need to understand and remove these effects from the observations. In my talk, I discuss the impact of ionospheric effects on LOFAR and why it is essential to correct for them. In the framework of the 'historical' development of ionospheric calibration methods in low frequency radio astronomy, I present the methods which are being considered to remove the ionospheric effects in LOFAR. Last but not least, I show several independent recent observations of the ionosphere with LOFAR.

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