Going Deep with ALFA E-ALFA Ultra-deep field group February 17, 2004 Abstract The improved sensitivity, RFI excisions and baselines expected with ALFA will open a new area of high sensitivity observations for the Arecibo Telescope. There is a significant scientific interest in single sight-line observations to unprecedented depth with integration times up to about 100 hours per beam. ... The total proposed integration time is 35 hours per beam. ... Higher sensitivity to unresolved sources. ...

... 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. ...