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The following table lists some general information on the ALFA receiver system. For technical details see the Performance Parameters web page.
Feed-horns | 7 beams arranged in an hexagonal pattern. Each beam has dual linear polarization; the polarization isolation is >20 dB |
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Beam size | 3.8 × 3.3 arcmin (beam 0) |
Bandwidth | 300 MHz |
Frequency range | 1225 - 1525 MHz. The low frequency limit is set to 1225 MHz by the waveguide cutoff and the OMT (orthomode transducer) performance; the high frequency limit is set to 1525 MHz by OMT resonances and a low-pass filter |
Filter bank | A 100 MHz filter (centered at 1440 MHz) is available for pulsar observing; the 1390-1490 MHz band is (almost) radar-free |
System temperature | ~30 K |
Gain | The central beam has higher gain (~11 K/Jy) than the peripheral ones (~8.5 K/Jy). The gain variation over the bandpass is +1/-2 dB |
Calibration noise source | The calibration is done by means of a single diode; the diode signal is splitted and injected into each beam. Tcal ~10-12 K (the stability of the diode is improved by maintaining its temperature constant) |
Array rotation | -100 deg to +100 deg |
Backend Processors | WAPP (Wideband Arecibo Pulsar Processor) - used for pulsar and spectral line work GALSPECT - used for Galactic HI work Mock Spectrometer - used for pulsar, continuum and spectral line work |