<?xml version="1.0" encoding="UTF-8"?>
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  <Identification_Area>
    <logical_identifier>urn:nasa:pds:context:instrument:asiago.copernico1m82.afosc</logical_identifier>
    <version_id>1.0</version_id>
    <title>AFOSC Polarimeter</title>
    <information_model_version>1.10.0.0</information_model_version>
    <product_class>Product_Context</product_class>
    <Modification_History>
      <Modification_Detail>
        <modification_date>2020-02-18</modification_date>
        <version_id>1.0</version_id>
        <description>Initial export from OLAF</description>
      </Modification_Detail>
    </Modification_History>
  </Identification_Area>
  <Reference_List>
    <Internal_Reference>
      <lid_reference>urn:nasa:pds:context:telescope:asiago.copernico1m82</lid_reference>
      <reference_type>instrument_to_telescope</reference_type>
    </Internal_Reference>
    <External_Reference>
      <reference_text>Desidera, S., E. Giro, U. Munari, Y.S. Efimov, A. Henden, A. Benetti, T. Tomov, A.
Bianchini, and C. Pernechele, Polarimetric evolution of V838 Monocerotis, Astron.
Astrophys. 414, 591-600, 2004.</reference_text>
    </External_Reference>
    <External_Reference>
      <reference_text>Pernechele, C., E. Giro, and D. Fantinel, Device for optical linear polarization
measurements with a single exposure, Proc. SPIE 4843, 156-163, 2003.</reference_text>
    </External_Reference>
  </Reference_List>
  <Instrument>
    <name>AFOSC Polarimeter</name>
    <type>Polarimeter</type>
    <description>The Asiago Faint Object Spectrographic Camera (AFOSC) Polarimeter consists of a
double Wollaston prism which splits the incoming light into four polarized beams at
0, 45, 90, and 135 degrees, separated by 20 arcsec.  These four beams are sufficient
to determine the Stokes parameters I, Q, and U simultaneously with a single exposure.
 

The CCD has 1024x1024 pixels (the pixel size is  24 microns), providing a total field
of view of 18.14x18.14 arcmin, with a pixel scale of 0.473 arsec/pixel.  The input
field has been masked at the telescope focal plane by a field selective mask to avoid
the overlap of the final images on the CCD detector.  

The four output beams emerge collimated from the double Wollaston prism and are then
focused on the CCD detector by the focal camera of AFOSC.  The final image is formed
by four strips from which the I, Q, and U parameters can be extracted.  From analysis
of several polarized and unpolarized standard stars, it is seen that the instrumental
polarization is fairly constant and always below 0.4 percent, while the systematic
errors in the position angle are below 1.5 degrees.</description>
  </Instrument>
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