Final Comments

The driftscan technique for spectral line surveying offers a number of advantages over pointed observations: (1) Data quality is maximized since the telescope is still relative to the ground; spillover, far sidelobes and on-axis gain are constant. (2) System stability can be monitored with high precision. (3) The observations are 100 percent efficient since data can be taken continuously. (4) The telescope scheduling is simple, and observing staff has little real-time responsibility, since the telescope is sitting still with the brakes on. (5) Spectral passband fluctuations due to standing waves (or any other instability that varies on time scales longer than a few minutes) can be tracked and removed, permitting observations to be made during the daytime. (6) The data is naturally processed in image-format; the analysis is very simple and efficient, and allows large projects to be tackled using existing software, which is proven and familiar.

á© Copyright Astronomical Society of Australia 1997