Multiple Drift Scans: A New/Old Method for Radio Continuum Observations in a Radome

This paper outlines a new applicaton of the technique of drift scanning, for single-dish radio continuum measurements within a radome. A radome scatters varying amounts of ground radiation into the receiver feed for di erent antenna positions, causing di cult-to-cancel total power uctuations as astronomical sources are tracked. Parking the telescope and allowing a source to drift through the beam largely eliminates this problem, and integration time can be built up by doing multiple drift scans on a given source. This technique has resulted in near-theoretical noise performance for the Haystack telescope, albeit with the rather low on-source duty cycle inherent in this technique. But even with the low duty cycle, multiple drift scanning has proven far superior to the standard radome-retrace beamswitching techniques used previously. Subject headings: Techniques: miscellaneous | radio continuum: general