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PACS FM-ILT SPECTROMETER SPATIAL CALIBRATION

PACS FM-ILT SPECTROMETER SPATIAL CALIBRATION. A. Contursi (H. Feuchtgruber). PACS Science Verification Review – 8/9 November 2007 MPE-Garching. TESTS EXECUTED. 3 27x27 rasters, ¼ pixel step, 3 chopper position, @ 0', +-3' (AOT), same grating position.

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PACS FM-ILT SPECTROMETER SPATIAL CALIBRATION

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  1. PACS FM-ILT SPECTROMETER SPATIAL CALIBRATION A. Contursi (H. Feuchtgruber) PACS Science Verification Review – 8/9 November 2007 MPE-Garching

  2. TESTS EXECUTED 3 27x27 rasters, ¼ pixel step, 3 chopper position, @ 0', +-3' (AOT), same grating position 3 9x9 rasters,1/4 pixel step, around central pixel FOV, 3 grating position, same chopper position @ 0'

  3. TESTS EXECUTION External BB @ 1000 °C Hole = 1.5 mm

  4. PSFs in every module Telemetry drop! no time for re-execution BLUE

  5. PSFs in every module Cross Talks with module 11. Present in all modules, all chop position Module 11 RED

  6. FMILT 1-2-3 comparison FMILT-1 FMILT-2 FMILT-3

  7. COMPARISON WITH THEORETICAL PSF Along chopper direction Observed BLUE Theoretical RED Mod 0 Mod 12 Mod 24

  8. COMPARISON WITH THEORETICAL PSF orthogonal to chopper direction Observed BLUE Theoretical RED Mod 12 Mod 0 Mod 24

  9. Spectrometer FOV fingerprint all spectral pixels averaged

  10. Rotation array-chopper direction NON LINEAR! The dependence of the rotation angle from the chopper position is not linear. Consistent with photometer results obtained with more chopper position

  11. Spectrometer FOV fingerprint each spectral pixel ½ pixel

  12. Spectrometer FOV fingerprint each spectral pixel ½ pixel

  13. Position of pixels in the sky chop +L chop 0 chop -L Assuming chopper commanded units, angle conversion Assuming XY stage to sky conversion: 1”= 0.18 mm

  14. Dependence on grating: BLUE

  15. Dependence on grating: RED

  16. Conservation of the flux Sum of 27x27 raster in each position after having normalized each raster to the PSF peak value Full dynamical range High cut BLUE homogeneous: 20% maximum variation

  17. Conservation of the flux Sum of 27x27 raster in each position after having normalized each raster to the PSF peak value Full dynamical range High cut RED: high signal (up to a factor of 2) from module 11 cross talk

  18. RASTER MAP RECONSTRUCTION !! CAUTION: not Flat Fielded !! GHOST! GHOST! ~< 0.1% of Bright Source

  19. GHOSTs in the BLUE ?? 1 moving ghost or 2 fixed ghosts ??

  20. RASTER MAP RECONSTRUCTION !! CAUTION: not Flat Fielded !! Background structures worse in the RED result in alignment problems: reconstructed PSF elongated Possible contribution from cross talk of module 11

  21. CONCLUSIONS Almost all optical misalignments successfully corrected Observed PSF widths as expected Chopper-array rotated by ~3 degree No dependency on grating position Cross talk module 11 in the RED Faint ghosts in the BLUE: potential concerns for weak extended sources

  22. OPEN ISSUEs Module 11 cross talks in the DUMMY and OPEN in RED and BLUE: sometime only in 1 supply group, sometime in all modules. Number of ghosts in the BLUE: 1 or 2? Which is their origin? Inside PACS or external window? (may be some answers in FS)

  23. Spectrometer Spatial Calibration in PV External BB @ 1000 °C corresponds to: 125 Jy at 77 micron 50 Jy at 154 micron This gives : S/N ~ 100 in the BLUE S/N ~ 12 in the RED Background levels: 3000 Jy in the BLUE 1700 Jy in the RED

  24. Spectrometer Spatial Calibration in PV Expected Herschel background level ~450 Jy at 77 micron (factor 6 less) ~175 Jy @ 154 micron (factor 10 less) Duration of 27x27 FMILT-3 raster ~2.5h Doubled in PV due to chopping to correct for responsivity changes due to glitches

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