description: The SDI4 has been offered since
P81 (April 2008). It is a combination of the SDI+
(see imaging, SDI/SDI+) and the 4 quadrant
phase mask (coronography),
optimized for the H-band. The purpose of this mode is to achieve high
contrast and improve detectability of faint sub-stellar companions
near bright stars, ideally down to massive extra solar giant planets,
by reducing the photon noise at small angular separation.
This is an example of the SDI4 science observations. Note the
characteristic 4 quadrant pattern of the SDI+ field-of-view each superposed with
the 4QPM_H mask.
This mode is offered in visitor mode and 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;
users are offered possibility to design the night time flat fields
taken immidiately after the science exposures to avoid problems with
instrument flexure;