Analysing first imaging data from LOFAR

Description and aim

LOFAR, the Low Frequency Array, is a next-generation radio telescope that is being built in the Netherlands and neighboring countries. It will carry out a broad range of fundamental astrophysical studies. An important goal of LOFAR is to explore the low-frequency radio sky by means of a series of unique surveys. The main aim of these surveys is to advance our understanding of the formation of galaxies, clusters and active galactic nuclei. These surveys will be carried out and scientifically exploited by a large international science team, consisting of 75 staff astronomers, 17 postdocs and 15 PhD students. Currently LOFAR is in its role-out phase. At the end of November, 12 stations were operational, and with the current projected rate of building, the complete LOFAR facility with 36 Dutch stations should be ready at the end of 2010. Also the main software pipeline that is capable of delivering maps of the radio sky from the basic data is advancing rapidly. The main challenge for the survey project is to ensure that high dynamic range thermal noise limited images with a stable point-spread function can be made over the entire accessible sky and over LOFAR's full frequency range. The serious issues that need to be tackled before deep and scientifically useful maps can be made include

 (i) an efficient usage of the computational resources,

(ii) an effective removal of radio frequency interference (RFI),

(iii) dealing with the corrupting influence of the ionosphere, and,

(iv) properly correcting for the station beams.

To deal with all these issues, the survey team has been and is organizing a series of `busy weeks’. The idea is that a team of astronomers from the survey team attempt to tackle a number of issues related to the challenges just mentioned. Three busy weeks have already been held (Aug 17-21, Sept 28-Oct 2, Oct 19-23). During these busy weeks very basic functionalities of the system were tested. The fifth busy week to be held at the Lorentz center (Jan 25-30) has the exciting prospect of having about 18 stations available. (The real number only depends on the weather: all the actual hardware is available, but can only be rolled out if there has not been too much rain).