Technical report

A fast mapping method for bolometer array observations at the IRAM 30-m telescope D. Teyssier, A. Sievers
Instituto de Radioastronomía Milimétrica, Avenida Divina Pastora 7, Núcleo Central, E-18012 Granada, Spain We present a fast-mapping method that can be used to map large fields with array receivers mounted in the nasmyth focus of the 30-m Telescope. This method was successfully tried using the 37-channel MPIfR Bolometer array during the winter 1999. Usually, maps are done in Azimuth, Elevation in such a way that a fully sampled map is obtained with each ``pixel'' of the array. All these maps are finally averaged to give a vastly oversampled final map. For this, we use vertical offsets (in elevation) of 4" or 5" between consecutive subscans (i.e. scanlines in azimuth). If we drop the requirement that the individual coverages fully sample the region to be mapped, one may use larger vertical offsets and still obtain a fully sampled final map. As we show in this technical report, a vertical offset of 23" is a good compromise when using the 37-channel bolometer. Examples of such maps are presented. For a given time one can thus observe a 6 times larger field than before. Instead of e.g. 6.5'$\times$5', a 15'$\times$13.5' field can be mapped within 1.5 hours.
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