Brazilian Tunable Filter Imager (BTFI) Preliminary Design Review (PDR)‏ USP-IAG Universidade de São Paulo 18-19th June 2008 Requirements Flow-down (Keith Taylor) Version 1.0

Science requirements Tunable Filter Imaging – 5 < R < 35,000 – FoV >3 arcmin (square) – Minimize number of blocking IFs Wavelength range (370nm < < 900nm) Semi-continuous range of R (quantized for the iBTF) IQ: – Seeing-limit: FWHM < 0.5” – GLAO: FWHM < 0.25” Efficiency <20 (peak)% ; <10% average – SNRs ergs.s -1.cm -2.arcsec Budgetary requirement – Design to cost

Design requirements flow-down (from Science) Wide-field TF requires FP or alternative – FP + iBTF chosen for their large A  (iFTS impractical) – FP I + FP P mode chosen to minimize # of IFs Wavelength range – EMCCD chosen to satisfy operational requirements in optical CCD domain Wide range of R (including R~20 and below) – FP + iBTF chosen to cover semi-continuous R-range IQ requirement – Optical design satisfies QI criteria for both SL & GLAO modes Efficiency requirement – Requires very good A/R (multi-layer) 16 refractive surfaces (after SAM but not including Filters, FPs or iBTF) – and mirror (enhanced silver) coatings 4 in 0 th order / 3 in 1st order (after SAM) SNR requirement – Need to reduce CIC noise (hence choice of CCCP-v2)

Operational requirements Data-cube rapid-scanning Rapid-scanning achieved with no loss of SNR – wrt classic CCD (slow read-out) – benefit from times of optimal SAM/GLAO PSF Can be easily spectrally calibrated Data ready for immediate science analysis On-the-Fly data reduction – for on-line data assessment Pipe-line data reduction – minimize requirement for off-line DR Mode changes <3 per night – Simplify manual exchange of FPs and filters

Design requirements flow-down (from Operations) Optimizing SAM performance while Rapid Scanning – EMCCD chosen to satisfy rapid-scan requirement and need to take optimal use of variable SAM PSF Ease of spectral calibration – Emphasis on well-specified and well-organised software procedures FPs notoriously difficult (investigate tunable calib. source from PhotonEtc) iBTF should be easier – but uncharted waters Well optimized and user-friendly OtF DR – EMCCD offers ability to assess SNR increase on-the-fly – Observer/On-line data-flow interaction - ergonomically optimized – Ability to quantify SNR as f n of time and position in the cube Pipe-line DR – DR slickness and speed -  - Scientific productivity Minimize mode changes – Cost requirement driven – Generally compatible with long data-cube acquisition

Interface requirements ( complies with SOAR ICDs ) Logistics – Support & training – Documentation – Operation & maintenance Opto-mechanical – space, weight & moment Electrical and electronic – motors, drivers, power supplies Detectors – Controllers – Monitoring – Cooling Software – System compatibility – User-friendly

Design requirements flow-down (from interfaces) Logistics – Documentation - requires management discipline (reviewed at CDR) – Training & Support – recommend special BTFI/SAM SOAR – Operation & Maintenance – project supplies spares + manuals Opto-mechanical – Space – complies by design – Weight/Moment – complies by analysis (FEA of SAM+BTFI+SIFS or SAMI) Requires SOAR Board approval Electrical and electronic – By design – confirmed through periodic Interface Reviews Detectors systems – By design – confirmed through periodic Interface Reviews Software systems – By design – confirmed through periodic Interface Reviews