Daily Image
13-06-2007
Entering the 4C catalog
| Submitter: | Sarod Yatawatta and Jan Noordam |
| Description: | Here is the 3rd in our deepening series of all-sky LOFAR/CS1 images (see 23/5 and 20/4). As before, CS1 is an array of 16 individual dipoles and one 48-dipole station, with a maximum baseline of 500m. This image combines two 24 hr observations, and 36 152 kHz subbands between 40 and 60 MHz. The resulting noise-level is 0.5 Jy, revealing all 3C sources (annotated in blue) and a fair number of 4C and other sources. As before, Cas A has been removed completely from the center, while the 2% residuals around Cygnus A (on the right) are due to the fact that this source gets very close to the horizon for part of the observation. The phase center and the 48-dipole station beam were tracking Cas A. After subtracting the two bright sources using their own calibration solutions, the uv-data residuals were corrected using the calibration solution valid for the direction of Cas A. Note the PSF sidelobes that are now visible above the noise around some of the brighter 3C sources, like 3C10 (Tycho, left of center) and 3C84 (Perseus A, left). On the far left, the Sun is in evidence. More and more bright sources will have to be subtracted from the uv-data in deeper images. |
| Copyright: | LOFAR |
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