brazilian tunable filter imager (btfi) preliminary design review (pdr) usp-iag universidade de são...
Post on 18-Dec-2015
214 Views
Preview:
TRANSCRIPT
Brazilian Tunable Filter ImagerBrazilian Tunable Filter Imager(BTFI)(BTFI)
Preliminary Design Review (PDR)Preliminary Design Review (PDR)
USP-IAG Universidade de São USP-IAG Universidade de São PauloPaulo
18-19th June 200818-19th June 2008
BTFI Data ReductionBTFI Data Reduction(Keith Taylor)(Keith Taylor)
Design Philosophy(Optimize Science Impact)
FPs notoriously difficult to calibrate, regularize and interpret: iBTFs are unheard of – doesn’t help; How do we tackle “fear of the unknown”?
Develop intuitive approach to problem Lots of graphical feed-back – “Picture = 103 words” Lead user through process “by the nose” Heavy use of procedural macros Minimize trips to the Nasmyth platform Make user feel they are in familiar Spectrograph-Land
Propaganda (catch-phrase is Think Slick)
How do we achieve “Slickness”? Inherit code without fear or favour
French, Canadian, French-Canadian, Australian (TAURUS c1980 not available!)
Deploy lots and lots of post-doc time (it’s free) in Brazil ; at SOAR
Over-arching Goals(Calibration)
Efficient calibration of FPs require:1. Calibration sources (line & continuum ; wide-field & point)
2. Slick parallelism determination (daytime only?) FPI & FPP (different procedures & algorithms) Stability of SESO FPs unknown
3. Slick gap (FP order) determination (daytime only?) FPI & FPP (different procedures & algorithms) Need to iterate on gap determination?
Slick -calibration (how often?) -calibrated data-cube – for -correction (daytime, only) 3D flat-fields
Efficient calibration of iBTF requires: 1, 4, 5 & 6 – ie: much simpler than FPs (hopefully!)
Over-arching Goals(Observing)
Efficient observing requires: Slick ITC
– on/off-line Slick acquisition
- Field position + 0, , & STEP
On-line data assessment (continuously updated during acquisition) SNR(,time) in multi-RoIs
On-the-Fly data reduction (next integration time-scale) for acquisition assessment and immediate feedback
Pipe-line data reduction (next night) State-of-the-Art
Off-line data reduction (for the anally retentive) Toilet paper not supplied
Archiving See comments by Chris Smith (NOAO)
Strategies to achieve goals(FP Parallelism)
FPI parallelism determination (low-R) SOAR’s ISB calibration unit (with fibre-feed modification)
NB: Small gap – no by eye method Use 4 corner-mounted (flexure) fibres Scan rapidly over line ; determine 4 -centroids ; iterate controller
(x,y) offsets until 4 -centroids are equal parallel
FPP parallelism determination (High-R) SOAR’s ISB calibration unit (wide-field) Mexican (hat)trick?
4 prisms in pupil filter wheel
or Pupil re-imager (practicality?)
Mexican (hat)trick
Left the FP is parallel. Right is not
PUMA
Further strategies to achieve goals
FP gap/order determination Calibration sources (line): SOAR’s ISB calibration unit (full-field or fibre-feed)
Need at least 2 lines (1, 2 …) widely spaced Scan FPI or FPP over FSR
Robust algorithm to determine FP gap Determine -calibration (locally)
PhotonEtc’s tunable source? ($50k?)
FP -stability (periodically through night if nec.) FPI – repeat parallel determination FPP – determine Ring Radius (classic technique)
FPI + FPP - tandem (coordinated) scans Needs -calibration for both I P but I = P zSTEP
I zSTEPP
Yet further strategies to achieve goals
iBTF calibrations Determine -calibration (single order – should be simple) Determine -map (~1D)
Slick ITC – on/off-line Includes models of all instrument & detector modes Includes all sky params (sky brightness, moon, extinction etc) Includes magnitude or surface-brightness switch
On-line data assessment (during acquisition) EMCCD (amp. mode) – view SNR increase on-line
Don’t have to wait for next CCD read-out
On-line z-compressed image (cf: TAURUS + IPCS: c1980) Select RoIs (~4-6) interactively Assess SNR of -profiles (not -corrected) on-line
Data Reduction (at last)
Preliminaries (during afternoon, for all configs.) -calibration (FPs and/or iBTFs) -map (FPs and/or iBTF) 3D flat-fields (FPs and/or iBTF) - -corrected
Acquisition protocols 3D data-cubes recorded as individual 2D frames
OtF data-cubes are not necessarily archived
On-the-Fly (during & immediately after acquisition) CR rejection (sigma clipping) on each individual z-frame Shift&Add into data-cube taking into account
Flexure determination (at least once per pass through data cube) Guiding corrections (gaussian fits to bright stars)
Interactive 2D gaussian fitting to field stars Interactive -profile fitting and SNR determination
Applying -correction on each RoI
The Pipe
Post-acquisition processing (next day) Flat-fielding (2D) individual frames – from Twilight? CR rejection (median rejection over 3 frames) Shift & Add (x,y,) into data-cube -correction 3D flat-field correction -calibration Sky-subtraction (in 3D - mainly for iBTF and FPI modes) Flux calibration (assuming calibration sources have been observed) -profile function fitting
Adaptive binning Wavelet analysis (?)
2D maps of flux, velocity, line-width etc. Rotation curve fitting (in your dreams!)
The Archive(email between: Steve Heathcote / Chris
Smith) Steve: “Needs to be able to swallow
40GBytes/night of data and transport it back to the archive?”
Chris: “Yes. We are committed to producing a "Data Transport System" (DTS) interface that can swallow at least the 300-400GB/nights by 2010”
Steve: “What software/hardware they will need for running this kind of pipeline.”
Chris: Hardware: “Basic Linux cluster, being a rack of 1U
units, each sporting 1 or 2 quad-core CPUs” Software architecture options:
1. “MOSAIC/NEWFIRM pipeline infrastructure” or 2. “LSST software”
top related