Daily Image
23-05-2007
Where is Cygnus A?
| Submitter: | Sarod Yatawatta and Ger de Bruyn |
| Description: | This is the first image to emerge from the prototype LOFAR processing pipeline. For the moment, this includes flagging, 2-source calibration, and imaging. Compare this image to the earlier LOFAR/CS1 image on April 20th. There, Cas A was subtracted completely from the field centre, but there were some 1% remnants of Cygnus A at the right. These have now disappeared by the simple expedient of not using data where the source is close to the horizon. The brightest source in that area of the image is now a supernova remnant close to Cygnus. However, there are now some residuals south of the position of Cas A. One possibility is that these are due to the presence of the rising Sun (on the left). This image has about the same noise (~3 Jy) as the last one. The total bandwidth is 0.5 MHz, around 55 MHz, and the total integration time is 9 hours. The observation did only include single-dipole "stations", i.e. it did not include the one 48-dipole station that was used before. The latter would only increase the sensitivity in its smallish (7 degree) beam. But its extra sensitivity does not appear to be essential for the selfcal solution. |
| Copyright: | LOFAR |
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