NATIONAL ASTRONOMY AND IONOSPHERE CENTER . ... The Arecibo Observatory is part of the National Astronomy and Ionosphere Center (NAIC), a national research center operated by SRI International, USRA and UMET, under a cooperative agreement with the National Science Foundation (NSF). ... As the site of the world's largest single-dish radio telescope, the Observatory is recognized as one of the most important national centers for research in radio astronomy, planetary radar and terrestrial aeronomy. ...

... 2.3 Data acquisition Spectra generated by the Multibeam correlator contain the usual structure seen in spectra from other H i instruments: a bandpass spectrum which is the sum of the sky , ground and receiver temperatures multiplied by the product of the filters in the receiver chain; superimposed on this is a noise ... Note also that sources extended much beyond ,40 arcmin can be imaged poorly in HIPASS images because of the bandpass sidelobe effect described in Section 3.3. ...