GPI Observing Modes ======================== The GPI instrument control software uses observing modes (FITS keyword ``OBSMODE``) to specify sets of instrument optical masks that work together. Each obsmode consists of a unique set of 4 elements: {Filter, Apodizer, Focal plane mask, Lyot Mask}. Obsmodes come in several basic flavors: * *Coronagraphic* observations, most common for GPI. * *Direct* observations, with no coronagraphic masks in use. * *Unblocked* (unocculted) observations, which use the coronagraphic Apodizer and Lyot mask but not the focal plane masks. These are occasionally used, mostly for certain types of calibration observation * *NRM* modes for non-redundant mask interferometry * and a single *Dark* mode for detector calibrations. The defined Obsmodes are as follows. See :ref:`reference_coronagraph` for details on the individual elements. ============ ======= ============== ======= ============== Obsmode Filter Apodizer FPM Lyot Mask ============ ======= ============== ======= ============== Y_coron Y APOD_Y FPM_Y 080m12_03 J_coron J APOD_J FPM_J 080m12_04 H_coron H APOD_H FPM_H 080m12_04 K1_coron K1 APOD_K1 FPM_K1 080m12_06_03 K2_coron K2 APOD_K2 FPM_K1 080m12_07 H_starcor H APOD_star FPM_H 080m12_03 H_LIWAcor H APOD_HL FPM_K1 080m12_04 Y_direct Y CLEAR SCIENCE Open J_direct J CLEAR SCIENCE Open H_direct H CLEAR SCIENCE Open K1_direct K1 CLEAR SCIENCE Open K2_direct K2 CLEAR SCIENCE Open Y_unblocked Y APOD_Y SCIENCE 080m12_03 J_unblocked J APOD_J SCIENCE 080m12_04 H_unblocked H APOD_H SCIENCE 080m12_04 K1_unblocked K1 APOD_K1 SCIENCE 080m12_06_03 K2_unblocked K2 APOD_K1 SCIENCE 080m12_07 H_starunb H APOD_star SCIENCE 080m12_03 H_LIWAunb H APOD_HL SCIENCE 080m12_04 NRM_Y Y NRM SCIENCE Open NRM_J J NRM SCIENCE Open NRM_H H NRM SCIENCE Open NRM_K1 K1 NRM SCIENCE Open NRM_K2 K2 NRM SCIENCE Open DARK H APOD_H FPM_H Blank ============ ======= ============== ======= ============== Note that there are some "experimental" modes which are rarely, if ever, used. These are * The "H Large Inner Working Angle" mode, which pairs the H band filter with the K1 focal plane mask and a specially optimized apodizer; in essence trading off worse inner working angle for (possibly) better starlight suppression. * The "H Star" mode, which uses a shaped pupil binary apodization which is theoretically equivalent to the regular H_coron apodization. These modes are essentially uncommissioned and are not recommended for general use. See also the `Gemini page on GPI observing modes `_.