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Pointed on-off observations with filled arrays would permit chopping on
the array, increasing the on-off observing efficieny by a factor 2
compared with the current systems where the off beam typically falls
between the pixels. If improving the sensitivity of on-off observations
were of high priority, several modifications could improve the
efficiency of the existing, sparsely sampled arrays significantly:
- A modification of the secondary reflector rotation control could
enable the co-rotation of the field, and thereby the chopping between
two bolometers even on undersampled arrays in the Nasmyth focus.
- Continuous fast sampling of data would permit the usage of up to
50% more data than what is now used during the observations. The
current modus is forced by the fact that the telescope data (DAPs) are
not available between subscans.
Frank Bertoldi
2002-08-21