High Precision CCD Imaging Polarimetry

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Session 10 -- Remote Observing, Ground-Based Telescopes and Instruments
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

[10.09] High Precision CCD Imaging Polarimetry

A. M. Magalh\~aes, C.V. Rodrigues, V.E. Margoniner, A. Pereyra (U. S\~ao Paulo), S. Heathcote (CTIO), G.V. Coyne (Vatican Obs.)

We describe a recent modification to the direct CCD Cameras at CTIO and LNA (Brazil) observatories in order to allow for high precision optical polarimetry. We make use of a rotating achromatic half-wave plate as a retarder and a Savart plate as analyser. Cancellation of sky polarization and independence of the CCD flat field correction are among the advantages of the arrangement. We show preliminary data that indicate the high polarimetric precision achievable with the method for non-extended sources. We give a brief description of the on-going observational programs employing the technique. Polarimetry of extended objects can be performed by using a Polaroid sheet in place of the Savart plate. Use of the Savart plate with such fields can also be valuable in the reduction, and analysis, of the extended source images as it provides polarization data on the non-extended objects in the field.

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