Daily Image
18-11-2009
The LBA and HBA LOFAR Sky Above Effelsberg
| Submitter: | James M Anderson |
| Description: | Moving up to higher frequencies... The international LOFAR station at Effelsberg has its full complement of 96 low band antennas and 96 high band tiles. Although each low band antenna always "sees" the entire sky, the high band tiles normally work in such a way that each tile only sees a limited area of the sky, about 20 degrees across, depending on frequency. Thus, for normal operations, full-sky imaging is not possible for the LOFAR high band. However, it is possible to place the high band tiles in a significantly less sensitive mode where only a single antenna per tile is used, thus allowing all-sky observations to be made. The movie being shown was made by scientists at the MPIfR in Bonn, Germany using the Effelsberg station on the afternoon of 2009 Nov 10. It shows a series of snapshot images made at individual frequencies. The frequencies go from 35 to 80 MHz, and from 110 to 190 MHz, in approximately 4 MHz steps. Each higher frequency step was made at a slightly later time, so that a small amount of sky rotation can be seen as well. The low frequencies have a very large synthesized beam and have strong emission from the Galactic plane, while the higher frequencies have smaller beams and less relative contribution from the Milky Way. The images have been self-calibrated on Cyg A and Cas A, but have not been deconvolved. (You can see many convolution artifacts in the images.) |
| Copyright: | James M Anderson/MPIfR |
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