Operation Concepts Definition Document (OCDD)Chip KobulnickyUniversity of Wisconsin

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Operational Mode DescriptionOperational modes are fully characterized by the configuration of 4 primary subsystems (basis vectors in 4-D) which describe the dataset being acquired.Focal Plane Elements (spatial)Dispersive Elements (spectral)Polarizing Elements (polarization)Detector (time)

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Focal Plane Mechanism O Open (implies direct acquisition & peak-up) S Slit (Reflective Longslit Plate; implies visual acquisition & peak-up) M Multi-slit mask (non-reflective carbon fiber; implies blind peak-up)Dispersive Elements I Imaging (none) (Implies no camera articulation) F Fabry-Perot Etalon (Implies no camera articulation) G Grating (Articulated camera)Polarization Elements U Unpolarized measurement (quartz block in place of waveplates) L Linear polarization measurement (1/2 waveplate; max 4 spatial field) C Circular polarization measurement (1/2 and waveplate; max 4 spatial field) A All-stokes mode (both waveplates operational in sync; 4 spatial field)CCD subsystem (see detector ICD for full explanation of readout modes) N - Normal readouts with exposure times of at least 3.6 s. Standard 2x2 binning H - High time resolution with frame-transfer in operation; max 4 spatial field with lower half masked; objects confined to small region of chip just above CTB; continuous readout. V - Vertical shift operations, including vertical charge shuffling in conjunction with telescope nods to perform high-quality sky subtraction (spectroscopy) or off-band subtraction (Fabry-Perot spectroscopy), or time-series spectroscopy or spectropolarimetry. D - Drift scan or arbitrary charge-shuffling in use; CCD is clocked at a sidereal rate

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Available Operational Modes

Focal PlaneDisperserPolarizationCCD readoutCommon NameCommission?OIUNImagingYMIUHHigh Time Resolution ImagingUMILNImaging Linear PolarimetryUMILHHigh Time Resolution Imaging Linear PolarimetryUMICNImaging Circular PolarimetryUOFUNFabry-Perot Spectroscopic ImagingYMFLNFabry-Perot Spectroscopic Imaging Linear PolarimetryUMFCNFabry Perot Spectroscopic Imaging Circular PolarimetryUSGUNLongslit SpectroscopyYSGUHHigh Time Resolution Longslit SpectroscopyYSGLNLongslit Linear SpectropolarimetryUSGLHLongslit High Time Resolution Linear SpectropolarimetryUSGCNLongslit Circular SpectropolarimetryUSGCHLongslit High Time Resolution Circular Spectral-PolarimetryUMGUNMulti-slit spectroscopyYMGUHMulti-slit High Time Resolution SpectroscopyUMGLNMulti-slit Linear SpectropolarimetryYMGCNMulti-slit Circular SpectropolarimetryUOIUDDrift Scan Imaging & spectroscopyU

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Focal Plane MechanismsO Open (direct imaging applications, Fabry-Perot spectroscopy) 2048 2048 2048 Impalas Detector Layout with 8 diameter FOV40964

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Table 1. Complement of Standard Reflective Focal Plane PlatesS Slits (reflective tiled longslit plates)~9 held in focal plane magazine

Reflective Slit Plate #LengthWidth ()17.50.45 27.50.637.50.947.51.157.51.367.53.07 Central 41.1 (variable) for spectral polarimetry8 12 above CTB1.1 (variable) for high speed spectroscopy9 41.1 w/ coronographic center

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Table 2: Standard Slitmasks M carbon-fibre focal plane masks Laser-cut slits slit width: 0.11 0.35 mm Standard Slitmask #2: Slitmask covers upper and lower of FOVStandard Slitmask #1: Slitmask covers lower half of FOV

#ConfigurationUse1Masks lower 4 x 8High Time res. Imaging2Masks upper and lower 2 x 8 (central 4x8 visible)Imaging and Fabry-Perot PolarimetryUp to 30 other user-designed masks

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Dispersive ElementsI Imaging (none) (Implies no camera articulation)

F Fabry-Perot Etalon (Implies no camera articulation)

G Grating (Articulated camera)1 of 6 gratings

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Polarizing Elements

U Unpolarized measurements (quartz block in beam)

L Linear polarization (half-waveplate; rotates through 8 positions)

C Circular polarization (half- and quarter-waveplate)

A All-stokes mode (synchronized half- and quarter-waveplate)

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CCD subsystem readout modes N - Normal readouts Readout time 3.6 s standard 2x2 binning, 5e- read noise 11.2 s standard 2x2 binning, 3e- read noise 22.1 s 1x2 binning, 3e- read noise

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CCD subsystem readout modes H - High time resolution with frame-transfer in operation; max 4 spatial field with lower half masked, and possibly upper portions masked as well.Bin RdN Read-------------------------1x2 3e- 11.0 s2x2 3e- 5.5 s1x2 5e- 3.2 s2x2 5e- 1.6 s

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CCD subsystem readout modes H all but a subsection of chip maskedBin RdN Read-------------------------1x2 3e- 11.0 s2x2 3e- 5.5 s1x2 5e- 3.2 s2x2 5e- 1.6 s

2x2 5e- 2.0 field 0.80 s 0.5 field 0.20 s 0.12 field 0.05 s (64 pix)(but image smear during 0.05 msec per row transfer)

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CCD subsystem readout modes V - Vertical shift operations, including vertical charge shuffling in conjunction with telescope nods to perform high-quality sky subtraction (spectroscopy) or off-band subtraction (Fabry-Perot spectroscopy), or time-series spectroscopy or spectropolarimetry.

D - Drift scan or arbitrary charge-shuffling in use; CCD is clocked at a sidereal or other rate

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Example of longslit spectroscopic mode operationTypical sequence of operation: Setup Telescope & Instrument (LOW OVERHEAD DESIGN GOAL FOR QUEUE MODE) Rotate telescope in Azimuth to correct location (few min; rate-limiting action) Select & insert filter (43 s) Select & insert grating (25 s) Select & insert longslit plate to be used (50 s) Articulate camera to desired position angle (3.6 s total readout time

Target acquisition: By guide probe, and using visual peak-up with SALTICAM as slit viewing camera.

Tracking During Exposures: By guide probe, or by reflected light from slit viewed by SALTICAM.Simultaneous!

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Example of multi-slit (slitmask) spectroscopic mode Setup Telescope & Instrument Rotate telescope in Azimuth to correct location (few min; rate-limiting step) Select & insert filter (43 s) Select & insert grating (25) Select & insert slitmask to be used (50 s) Articulate camera to desired position angle (3.6 s total readout timeTarget acquisition: By SALTICAM, guide probe, and dithered exposure peak-upTracking During Exposures: By guide probeSimultaneousPeak-up performedIn spectral mode

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Instrument Commissioning PlanLet science drive commissioning Goal:6 science programs corresponding to each major instrument modeStart with simplest modes (i.e., imaging)Fully commission all basic modesLeave specialized modes to users for shared-risk basisReduction Software: standard community tools

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Overview of Modes Commissioned by Instrument TeamEst Time. Mode Science Program----------------------------------------------------------------------------------------3 d Imaging TBD Nordsieck5 d Longslit Spectroscopy TBD Kobulnicky4 d High Time Res. Spectroscopy Magnetic CVs Buckley4 d Fabry-Perot Spectroscopy TBD Williams 4 d Multi-slit Spectroscopy PNe in Nearby Galaxies Kobulnicky5 d Polarimetric Imaging/Spectra Be Stars in the LMC Nordsieck25 d (on telescope; based commissioning for other major instruments)

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Other possible user-commissioned modes (extensions of team-commissioned modes)

High Time Resolution Spectral-Polarimetry Fabry-Perot Spectral-PolarimetryCircular polarimetryCircular Spectral-PolarimetryAll-stokes PolarimetryHigh Time Resolution Multi-slit Spectral PolarimetryShift+nod high-precision spectroscopyDrift scan imaging

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Commissioning tasks not requiring all mirror segments - acquisition strategies - software interfaces - focus, optical distortion, vignetting tests - wavelength calibration & stability - tracking & guiding stability

Commissioning tasks requiring all mirror segments - instrumental polarization calibrations - total sensitivity calibrations - final flatfield calibrations & variability - other aspects sensitive to pupil illumination

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Calibration IssuesWavelength: He, Ne, Ar, Cu lamps fed to diffuser before moving baffle

Flatfields: Continuum lamps fed to diffuser before moving baffle Flats taken next morning by re-creating actual science tracks w/baffle Observing scripts stored for easy reproduction (only a subset of spectrophotometric observations will need thisprecision)

Observatory superflats created periodically in standard configurations -> enable differential flats taken on nightly basis

Stray/scattered light? TBD during commissioning

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