The seven beam system was primarily optimized to perform Beam-Park experiments. Using the Tracking and Imaging Radar (TIRA) telescope, space debris at an altitude of about 200 km are illuminated. The Effelsberg multi-feed system receives the reflected signal of these space debris. Using the TIRA-Effelsberg combination space debris down to a linear size of 1 cm can be investigated (D. Banka, L. Leushacke, D. Mehrholz, Beam-Park-Experiment 1/2000 with TIRA, Space Debris 2, 83).
Observing time is an expensive quantity. Accordingly, we optimized EBHIS to provide valuable
data for a broad scientific community. For this purpose, we decided to use the
maximum of the available bandwidth and FPGA-spectrometers to obtain high-quality
data because of
1. short integration times of less than a second: this allows us to clean the data for the bulk of the RFI events, because they are variable in time, frequency, and polarization.
2. an order of magnitude more spectral channels than classical auto-correlators, this provides the chance to map narrow spectral lines within a huge bandwidth range.
The maximum EBHIS bandwidth is 100 MHz. The 14 FPGA spectrometers offer for each polarization 16.384 spectral channels, providing a corresponding velocity resolution of 1.3 km/s. This is sufficiently narrow to resolve even the coldest CNM-structures belonging to the Milky Way. The 0.5 sec integration time overcomes, in combination with the 8-bit dynamic range, even the strongest recorded RFI-events. Multiple coverages of the survey area will allow to correct for the contribution of the stray-radiation received by the near and far side-lobes of the single dish. Applying a proper stray-radiation correction allows to reach an accuracy level equivalent to a 99% main-beam efficency. We are using frequency switch observations with 4 MHz frequency shift. The covered velocity range is -1000 to +20000 km/s.
We observe fields of five by five degrees in angular size. For the Milky Way survey we use a scanning speed of four degrees per minute. Two coverages are sufficient to reach our final sensitivity limit for the Milky Way survey part accordingly. During the observations the feed orientation is permanently optimized to warrant the full angular sampling. In regular time intervals we observe the standard position S7 for an absolute calibration of our data. In between the noise-diode is used for relative calibration. Test observations disclosed the stability of the whole receiving system lasting for several hours. Across the whole bandpass we reach today a calibration accuracy of about 3%.