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The Prime Focus Imaging Spectrograph for the Southern African Large Telescope: Operational Modes Chip Kobulnicky – Instrument Scientist, University of Wisconsin PFIS Team Kenneth NordsieckPI – University of Wisconsin Eric Burgh Instrument Scientist – University of Wisconsin Darragh O’Donoghue Detector PI - South African Astrophysical Observatory Michael Smith Instrument Engineer – University of Wisconsin Jeffrey Percival Project Manager – University of Wisconsin Ted Williams Fabry-Perot PI – Rutgers University
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PFIS Overview First-generation, all-purpose spectrograph on the Southern African Large Telescope (SALT). Commissioning in fall 2004. First-generation, all-purpose spectrograph on the Southern African Large Telescope (SALT). Commissioning in fall 2004. Optical imaging spectrograph 3200Å - 9000Å 3200Å - 9000Å 8’ Field of view 8’ Field of view All-refractive collimator & camera All-refractive collimator & camera (see 4841-164, Burgh et al., for optical design of PFIS) optical design of PFIS)
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PFIS Schematic Subsystems: 1. Focal Plane open longslit custom slitmask 2. Polarization Optics open (quartz block) ½ wave plate ¼ wave plate ½ & ¼ wave plates + polarizing beamsplitter 3. Dispersive Elements none (unarticulated) 5 VPH gratings Fabry-Perot etalon(s) 4. CCD Detector normal readout frame transfer charge shuffle Planned Future Upgrade
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PFIS Operational Modes Imaging Grating Spectroscopy CCD Readout Mode Observing Mode FocalPlaneUnit FieldWaveplat FocalPlaneUnit FieldWaveplat Normal Readout (<0.25 Hz) Filter Imaging none8’N Longslit Spectroscopy slits 1-6 8’N Fabry-Perot Imaging none8’N Multi-slit Spectroscopy mask8’N Imaging Polarimetry Mask 2 4’Y Longslit Spectropolarimetry slit 7 4’Y Fabry-Perot Polarimetry Mask 2 4’Y Multi-slit Spectropolarimetry mask4’Y Frame Transfer (fast; ~1 Hz) Fast Filter Imaging Mask 1 4’N Fast longslit Spectroscopy slit 8 4’N Fast Fabry-Perot Imaging Mask 1 4’N Fast multi-slit Spectroscopy mask4’N Fast Imaging Polarimetry --- Fast Longslit Polarimetry --- Fast Fabry-Perot Polarimetry --- Fast Longslit Spectropolarimetry --- Charge Shuffle (very fast; up to 20 Hz) V. Fast Filter Imaging mask”N V. Fast Longslit Spectroscopy slits 1-8 ”N V. Fast Fabry-Perot Imaging mask”N V. Fast Multi-slit Spectroscopy mask”N V. Fast Imaging Polarimetry mask”Y V. Fast Longslit Spectropolar. slit 7 ”Y V. Fast Fabry-Perot Polarimetry mask”Y V. Fast Multi-slit Spectropolar. mask”Y Forbidden modes
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λ Coverage & Spectral Resolution Contours at 90%, 70%, 50% efficiency. Assumes 1.25” slit, α max =45 deg 4500 1500 3000 R Redshift surveys Nebular abundances Planetary nebula kinematics & abundances Ca H&K, [O II] kinematics z = 1.6 Ly α z = 1-2 restframe UV Bowen florescence Ca II stellar kinematics
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1.2” seeing 0.7” seeing Spectral Resolution vs. Throughput
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780 l/mm VPH grating: efficiency and wavelength coverage Field center -2’ field angle +2’ field angle
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Readout Modes and Times Normal readouts: 4096 x 6044 pixels – 3.6 s with 5e- read noise Frame Transfer: 2048 x 6044 pixels – 1.8 s with 5 e- readnoise Image Height (arcmin) Image Height (pixels) Readout Time (s) 4.020481.595 2.010240.797 0.52560.199 0.125640.050 2048 2048 2048 Image field 4’ Charge transfer buffer See 4841-052, O’Donoghue et al. for detector details High Time Resolution
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Fabry-Perot Spectroscopy 3 F-P Etalons 3 F-P Etalons R=500 tunable filter R=500 tunable filter R=2500 (dual etalon) R=2500 (dual etalon) R=12000 (dual etalon) R=12000 (dual etalon) 4300 Å – 8600 Å Star cluster kinematics Galaxy cluster kinematics (z>0.4) Flows in SF regions & galaxies F-P imaging polarimetry of reflection nebulae (PI - Ted Williams, Rutgers)
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Polarimetry (See 4843-24 - Nordsieck et al.) Linear polarimetry – ½ wave plate, 8 positions Imaging polarimetry, 4’ FOV – polarimetric surveys Longslit spectropolarimetry – novae, magnetic stars, AGN Time-resolved polarimetry or spectropolarimetry – accreting binaries, AGN, GRB Circular polarimetry – ½ wave plate (8 positions), ¼ wave plates (2 positions) 2048 2048 2048 4096 4’ mask Focal Plane Detector
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PFIS Science & Summary Multi-object Rapid Readout Polarimetry Fabry-Perot Multi-slit spectral surveys (e.g., redshift surveys, stellar surveys) X Wide-field polarimetric imaging (e.g., Magellanic Cloud surveys) X Extreme blue λ galaxy kinematics & populations (z=1-2) X High time resolution spectroscopy (CVs, GRB, AGN) X High time resolution spectropolarimetry (CVs, GRB, AGN) X X Imaging spectropolarimetry (novae, PNe, active galaxies) X X ?????
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1: Good morning, thanks for getting up so early to be here. This talk highlights the operational Modes and science niches for the Prime Focus Imaging Spectrograph under design At the university of Wisconsin destined for the Southern African Large Telescope, SALT. 12: Facility instrument, yet science niches! Exciting but scary thing is what the user will dream up to do with a versatile instrument.
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Signal-to-noise vs. Magnitude
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Efficiency
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Spectral Resolution vs. Throughput
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