... The distomats measure the average height of the platform every 2 minutes. If the average platform height is more than .04 inches from the nominal position, the tiedowns will pull (or release) equally on all 3 corners to bring the average height back to the nominal position. ... The platform corner height versus dome position (at fixed average platform height) shows that the platform corners move by +/- 6 inches just from the dome motion (this was before the alfa upgrade). ...
... 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. ...