Polarimetry is performed in a single user-defined waveband using either PHT-P (AOT PHT50) or PHT-C (AOT PHT51). The observations are made by observing the target through three separate polarisers having orientations of 0 deg, 120 deg, and 240 deg, respectively.
Observations can be made either in staring mode or rectangular chopping mode. In staring mode a raster observation may be performed.
These observing modes are dedicated to obtaining polarisation measurements of various sources. These can be point-sources like AGNs as well as extended polarised emission from star forming regions.
In addition to the polarimetric measurements, two measurements will be made of the target with no polariser in place in order to remove errors due to pointing drifts during the integration, and to provide a consistency check for the total flux derived from the polarisation vectors. The first of these measurements will be obtained before the polarisation measurements and the other one afterwards. These can be used for photometry of the source. The exposure time for one measurement without polariser is half of that for one polariser setting.
One FCS calibration measurement will be obtained at the end of the observation sequence.