Available Instrument Setups

Following instrument setups are available:

Linear polarimetry imaging using calcite (not usefull for extended objects!)

Circular polarimetry imaging using calcite (not usefull for extended objects!)

Linear spectropolarimetry

Circular spectropolarimetry

Linear polarimetry imaging using polaroids (for extended objects)

NOTE:
It is not possible to change between half wave and quarter wave plate during an observing run, but it is possible to do both linear and circular polarimetry simultaneously using the quarter wave plate, at the cost of ~50% loss of efficiency in the linear polarisation.

Following slits are available for spectropolarimetry:

Pol_1.0" (actual width 0.7")

Pol_1.4" (actual width 1.2")

Pol_1.8" (actual width 1.5")

all 15" long

NOTE:
Only one slit can be mounted at a time as there are only two calcites available!

Orientation of the Calcites:

By default, both calcites, the imaging calcite named "Calcite" and the spectroscopy calcite with a slitlet on top named "Pol_1.8", "Pol_1.4" or "Pol_1.0" are mounted such that the ordinary and extraordinary beam are split up horizontally ("Horizontal Mount"). For spectro-polarimetry the two horizontal slitlets are separated horizontally on the CCD producing two vertical spectra. With the new controller (June 2011) there is no issue with readout time. This mount has the advantage that grisms can be mounted in their default vertical orientation. In the period November 2008 to April 2012 we used the "Vertical Mount" to allow for fast spectro-polarimetry.