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radboud_current_astronomy_picture [2011/07/18 12:10]
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-====== Radboud Current Astronomy Picture ====== 
- 
-===== July 18, 2011: Fire in TV & radio tower seen in LOFAR data ===== 
-{{currentpicture:​hoogersmildetoren-tbb.jpg }} 
- 
-On July 15, 2011 the TV & Radio communication tower at Hoogersmilde in the 
-province of Drenthe caught fire and eventually collapsed. This caused 
-a major disruption of TV and radio service in the Netherlands. The 
-tower is located in the same province as the LOFAR radio telescope, 
-which was operational at the time measuring radio emission from cosmic 
-particles for the LOFAR Cosmic Ray Key Science project using the 
-transient buffer boards (TBBs). The TBBs allow one to record raw data 
-from all antenna and do offline processing after an event has 
-happened. The figure shows three radio spectra from low-band antennas 
-(LBAs) in the FM band with 1 kHz resolution right after the fire had 
-started: During the fire the signal strength goes down and then shuts 
-off completely. The data was taken through the side-lobes of the 
-antennas and through a low-pass filter to suppress the FM band, so is 
-highly suppressed, but nonetheless clearly visible. 
- 
-While Hoogersmilde was the strongest source of transmission at 
-low-frequencies,​ it had not caused major problems in LOFAR data since 
-proper measures had been taken to mitigate its radio frequency 
-interference (RFI). In fact, the LBA frequency range is rather free of 
-RFI. 
- 
----- 
- 
-Credit: H.Falcke, S. ter Veen 
- 
- 
-