Oct 17, 2001 SALT PFIS Preliminary Design Review 1 Operation Concepts Definition Document (OCDD) Chip Kobulnicky University of Wisconsin
Jan 12, 2016
Operation Concepts Definition Document (OCDD)Chip KobulnickyUniversity of Wisconsin
UW Foundation
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)
UW Foundation
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
UW Foundation
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
UW Foundation
Focal Plane MechanismsO Open (direct imaging applications, Fabry-Perot spectroscopy) 2048 2048 2048 Impalas Detector Layout with 8 diameter FOV40964
UW Foundation
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
UW Foundation
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
UW Foundation
Dispersive ElementsI Imaging (none) (Implies no camera articulation)
F Fabry-Perot Etalon (Implies no camera articulation)
G Grating (Articulated camera)1 of 6 gratings
UW Foundation
UW Foundation
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)
UW Foundation
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
UW Foundation
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
UW Foundation
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)
UW Foundation
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
UW Foundation
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!
UW Foundation
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
UW Foundation
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
UW Foundation
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)
UW Foundation
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
UW Foundation
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
UW Foundation
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
UW Foundation
UW Foundation
UW Foundation
UW Foundation