Fr.: permutation de lobe
In single dish radio astronomy, any technique which forms the difference of signals received from two (or more) pointings on the sky without physically moving the main reflector of the antenna. By rapidly forming differences between sky positions that do and do not contain astronomical sources, beam switching can minimize the corruption of spectral baselines by non-idealities in the instrumental frequency response, or of continuum observations by atmospheric fluctuations.
Fr.: permutation de fréquence
A mode of observation in radio astronomy in which the telescope remains at a fixed position and data is accumulated while the center of the receiver passband is switched between signal and offset frequencies. Data accumulated at the offset frequency is subtracted from the signal frequency data before storage as a frequency switched scan. → beam switching.
Fr.: permutation de position
In single dish astronomy, an observing mode in which the telescope is moved between the object position and a user defined reference position. The aim is to eliminate unwanted signals in the baseline. → beam switching; → frequency switching.
The act of changing one thing or position for another.
Verbal noun of → switch (v.).