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05-02-2010
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First imaging results from EMBRACE

Submitter: Stefan Wijnholds on behalf of the EMBRACE-team
Description: Recently, the EMBRACE team has reported successful validation of the analog tile beam former. Today, we demonstrate successful all-sky mapping with a 3x3-array at 1475 MHz. This 40 dB dynamic range image shows Afristar near the southeastern horizon as well as the grating response of the array in the North. The resolution has improved considerably compared to the single tile results shown earlier.

For this experiment, the tiles were scanning the sky on an (l,m)-grid with 0.02 resolution correlating their signals in a 195 kHz subband over 1 s integration using a LOFAR station backend. The pointing on Afristar was used to calibrate the delay and gain differences between the tiles while the autocorrelation powers were equalized for each pointing. The image resolution was increased to 0.004 by producing 5x5-pixel subimages around each pointing direction based on the covariance matrix. The total image shown here is a mosaic of these subimages.

Although much work still has to be done to understand all the intricacies of the EMBRACE system, this result demonstrates that the control software has reached sufficient maturity to start conducting real experiments with EMBRACE.
Copyright: ASTRON / EMBRACE
 
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