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Overview, Spectrometer Products and Processing Philosophy

PACS IFU Spectrometer. Overview, Spectrometer Products and Processing Philosophy. Phil Appleton on Behalf of PACS Team. PACS Spectrometer: The First IFU to L2!. PACS Integral Field Spectrometer (Poglitch et al. 2010). 5x5 pixels 1 pixel = 9.4”. FOV 47”x47”. SLICER MIRRORS.

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Overview, Spectrometer Products and Processing Philosophy

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  1. PACS IFU Spectrometer Overview, Spectrometer Products and Processing Philosophy Phil Appleton on Behalf of PACS Team

  2. PACS Spectrometer: The First IFU to L2!

  3. PACS Integral Field Spectrometer (Poglitch et al. 2010) 5x5 pixels 1 pixel = 9.4” FOV 47”x47” SLICER MIRRORS Simultaneous Blue and Red Coverage via diachroic GeGa Two (25 x 16) arrays Stressed and un- stressed Blue (55-98 m) Selectable band (3rd and 2nd Order) GeGa detectors Red (102-210m) 1st order

  4. PACS—Some Optical Components Calibration grey-body source (common with Photometer) Lithrow-mounted Grating recieves elliptical beam from anomorphic collimator Filter wheel assembly 8.5 grooves/mm 2720 grooves Chopper (common) max 6 arcmin throw

  5. Diffraction grating spectrometer with high- and low-stressed Ge:Ga detector arrays Grating: diffraction element used in 3 orders

  6. The Ge:Ga Photoconductor Arrays Stressed (R) and unstressed (B) photoconductors cooled to 1.65K in a 5 + 5 linear segments of 16 form the basic 25 spatial modules with 16 spectral pixels. The photoconductors are read-out at 256Hz via cold amplifier/multiplexer (CRE) CMOS circuit held at 3-5K. A complete assembled Ge:Ga detector assembly. Data is read out in 32 samples and slopes are fitted onboard to produce samples of 1/8s each for storage and transmission to the ground.

  7. Spectrometer Astronomical Observing Templates (AOTs) • Line Spectroscopy AOT:observation of individual narrow lines: PIPELINE • Chopping/nodding STANDARD (SLICED) PIPELINE • Pointed, dithered and mapping modes (optional special pointed) pipeline) • For isolated sources and rasters ≤ 6 arcmin • Variable grating sampling for faint and bright linesUnchopped mode • UNCHOPPED PIPELINE (Under dev) • For mapping observations of crowded fields • ON and OFF Source position provided • Range Spectroscopy AOT:observation of extended ranges, broad lines or continuum STANDARD (SLICED) • PIPELINE • Range scan (same concept as Line Spectroscopy) for broad lines • SED mode for continuum-like spectral scans covering huge range • Chopping/nodding • Pointed, dithered and mapping modes • For isolated sources and rasters ≤ 6 arcmin • Unchopped mode UNCHOPPED PIPELINE (Under dev) • For mapping observations of crowded fields • Optional off-position Signal modulation Techniques - Range definition Signal modulation Techniques

  8. Nod “B” Nod “A” Nod “A” OFF ON ON OFF Nod “B” Example of Chop/nod AOT blocks START observation Nod slew On-target slew Nodding “A” position Nodding “B” position Calib. 87 sec Line1 x 1 184 sec Line2 x 1 184 sec Line3 x 2 344 sec Line1 x 1 184 sec Line2 x 1 184 sec Line3 x 2 344 sec Repeat N times (number of cycles) 984 sec = grating up-down scan END observation … move to next raster position and repeat Pointing layout example of a nodding raster observation: Chopping/nodding pattern

  9. Spectrometer Data • PACS raw data is integration ramps with typically • 1/8 second reset interval (32 readouts) for bright sources/lines • the dynamic range can be adjusted by four integration capacitors • On-board averaging is required to fit within the allowed downlink telemetry rate • 32 readouts averaged • several “raw” ramps are downloaded in their entirety to provide “saturation” information. The raw pixels cycle through the array with time. PACS raw ramps

  10. Spectrometer Pipeline Level 0 first processing PACS data, House Keeping Level 0 Pointing Flag Data Permanently Bad pixels (few) When grating or chopper moving Saturated data When glitches present Open and dummy channels (spec 0, 18) Convert DNs to Volts/s Assign observing block labels (e. g. Nod positions, grating scan direction, calibration block, scan mode) Assign RA/Dec > pixel Level 0.5 Uncalibrated Data Frame

  11. Steps to Calibrated Frame Level 0.5 Wavelength Calibration Nonlinearities and Spatial Distortions Apply RSRF Flat Field correction Subtract On and Off Chop and Convert to Jy Transient Corrections Under investigation Level 1 Calibrated Data Frames (25 x 16 x time = grating movement)

  12. What are Level 1 Frames? Calibrated Frame is time history of spectral scan as seen by each pixel FRAMES 16 spectral Time 25 spatial pix 12

  13. { RAMPS → FRAMES averaged ramps provide frames 16 spectral pixels Grating scan = time 25 spatial pixels

  14. Level 0 -1 and 2 Products PACS PIPELINE CUBE BUILDING SINGS background FRAMES RAW Level 0 To Level 0.5 Projected to 3” x 3” pixels To calibrated L1 FRAMES CALIBRATED PACSCUBE REBINNED PROJECTED FRAME CUBE CUBE CUBE CALIBRATION PRODUCTS similar to B. Ali’s talk Level 1 Level 2

  15. Level 2Spectral Cubes Level 2 Spectral Cube

  16. PACS SPECTROMETER Pipeline usesSLICED FRAMES and CUBESThe concept of slicing was introduced because of the many dimension of data in a given AOR.The slices can be processed sequentially Possible Slicing “Dimensions” 1) Calibration block needed to have a separate slice. 2) Raster Mapping (Cube every IFU pointing). 3) In Chop-Nod you have NodA and NodB for every demanded position. 4) More than one line can be observed in one AOR. 5) Might want the option of separating the up and down scans of the grating 6) In unchopped mode “On” and “Off”

  17. How is this accomplished in HIPE 6.0 RC2 build Observational Context e. g. ( 2 x 1 raster and 2 line obs) slicedFrames = SlicedFrames(level0.fitted.getCamera(camera).product) perform Level 0.0-0.5 pipeline steps CALBLOCK REMOVED CalBlock APPLY SLICING RULE by raster/Nod Position/LINE_ID = cal block slicedFrame[0] slicedFrame[1] slicedFrame[2] slicedFrame[3] slicedFrame[4] slicedFrame[5] slicedFrame[6] NODA/NODB LINE 1 and 2 slicedFrame[7] slicedFrame[8] LINE 1 LINE 2 A B A B slicedFrame[0] slicedFrame[0] slicedFrame[1] slicedFrame[1] perform Level 0.5-1.0 pipeline steps slicedFrame[2] slicedFrame[2] slicedFrame[3] slicedFrame[3]

  18. Level 1-2 pipeline Manually select given line by line ID convert all raster frames and nod frames into sliced cubes for that line ID FINAL LINE Projected CUBES Make sliced rebinned cubes for for all rasters and nods for given line ID Rebinned cubes gathered into LIST Context SpecProject LINE1 Line 2 GRID RASTERS ONTO WCS SpecProject repeat for line 2 ...3...etc

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