| Station Baldy was the first POLFAR station to be commissioned. It received a lot of media attention because it was not only the first Polish LOFAR station, but it also contained the 100.000th LOFAR dipole (See http://www.astron.nl/dailyimage/main.php?date=20150824 ).
As a final test after connecting the new station to our European network, we decided to make an all-sky image with it, remotely from Dwingeloo. Since the HBA tile beam is only 20 degrees wide, we used a single dipole (out of 16) per tile, thus extending the view to 140 degrees. A program written by Michiel Brentjens selected the set of dipoles that minimised the station beam sidelobe level. After correcting for the dipole position offsets w.r.t. the center of their tiles, and applying the calibration tables, we could finally generate all-sky images.
The movie shows a 24h observation. It consists of 5s snapshots, taken at one-hour intervals. Only a single 1.2 kHz subband around 115 MHz was used.
The strong radio sources CasA and CygA, and our own Milky Way are clearly visible. Notice also our closest star (the Sun), moving from south-east to south-west. Most importantly, the horizon and the rest of the image are free from Radio Frequency Interference (RFI), even with a security camera installed on-site.
So the station is ready to be included in the International LOFAR Telescope (ILT). The three new POLFAR stations will definitely improve the LOFAR image quality, especially the spatial resolution.
|Astron & ATH