Switching modes and observation kinds

Switching is done in two main ways.

Position switch

where the off-measurement is done on a close-by sky position devoid of signal. Wobbler switching is a particular case.

Frequency switch

where the telescope always points towards the the source and the switching is done in the frequency (velocity) space.

Moreover, there are two main observation kinds.

Tracked observations

where the telescope track the source, i.e. it always observes the same position in the source referential. The result is a single spectra.

On-The-Fly observations

where the telescope continuously slew through the source with time to map it. The result is a cube of spectra.

In the following, we will work out the equations needed by the time/sensitivity estimator for each combination.