Novelties in the Call For Proposal for P80

  • Imaging polarimetry with the Wollaston_45 is restricted to point sources,
    due to the absence of the entrance mask, that used to mask out the field where the E- & O-vectors overlap.
  • The semi-transparent coronographic mask cannot be used with the S13 camera anymore.
    Indeed the mask has been re-aligned. As a consequence the 4 holes are placed at the 4 corners of the S13 field of view (FOV).
  • The 4QPM mask has been removed.
  • Two new four quadrant phase masks have been installed for coronography.
    These new masks contain a small classical Lyot stop, of equivalent radial attenuation of 0.2", in their center.
    One mask is optimised for K band and offers a field of view of 13x13". The other mask is optimised for H band obseravtions and has a 8x8" FOV.
    For both masks, the peak to peak attenuation is of the order of 100 on fiber and 20 on 'real' stars; which correspond to a gain of a factor of 2 compared to the old 4QPM mask.

    Contrast curve of the 4QPM_K (on a star)

    Contrast curve of the 4QPM_H (on the fiber)

  • A new SDI has been installed. It uses the same camera and thus the same filters as the 'old' SDI.
    Now each filter has a 8x8" FOV. This new mode uses a super-achromatic double Wollaston prism.
    A first estimation of the performance shows that it provides similar results as the old SDI,
    i.e. magnitude difference (at 1.575mu) of 10 at 0.5" and 11 at 1". Out of 2", one is read-noise limited.

Flatfield image of the 'old' SDI

Flatfield image of the "new" SDI (=SDI+ mode)