also wire grid polarimetry; has been discontinued since P82:
• DPR.TECH POLARIMETRY,WIRE_GRID; POLARIMETRY,WIRE_GRID,JITTER; POLARIMETRY,WIRE_GRID,CHOPPING

description: CONICA is equipped with a MgF2 Wollaston prism, used for imaging polarimetry, as well as a turntable half-wave plate. The Wollaston prism is located in the OPTI4 filter wheel (INS.OPTI4.NAME=Wollaston_00). Since the J-band filter is in the same wheel, J-band polarimetric observations are not possible. Also, the half-wave plate is installed in the CONICA's entrance wheel, where the calibration mirror is situated. Thus, internal calibrations with the half-wave plate cannot be done.

Wire grid polarimetry and the Wollaston_45 are no longer available (as of P82).

The Wollaston splits the incoming light into ordinary and extraordinary beams. An image taken with the Wollaston prism will contain two images of every object. To avoid sources overlapping a special mask consisting of alternating opaque and transmitting stripes is inserted in the optical path.

For more information regarding polarimetric mode of NACO consult the NACO User Manual and the instrument web pages.

	An example of the polarimetric observation with filter H, camera S27
	Polarimetric observations with filter Ks and camera S13. No Mprime observations are offered with polarimetry.

This mode is offered in service and visitor mode. It is not supported by the pipeline.

calibrations:The calibration plan includes

• standard detector darks with readout mode and DIT matching the one used for science;
• standard sky (twilight) flat fields without the polarimetric mask mask and without the polarizer; In VM twilight flats with half-wave plate can be requested; No internal lamp flats are offered, as the calibration mirror in the light path changes the level of polarization.
• nightly zero points;