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 0', +-3' (AOT), same grating position 3 9x9 rasters,1/4 pixel step, around central pixel FOV, 3 grating position, same chopper 0'

TESTS EXECUTION External 1000 °C Hole = 1.5 mm

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

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

FMILT comparison FMILT-2FMILT-1FMILT-3

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

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

Spectrometer FOV fingerprint all spectral pixels averaged

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

Spectrometer FOV fingerprint each spectral pixel ½ pixel

Spectrometer FOV fingerprint each spectral pixel ½ pixel

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

Dependence on grating: BLUE

Dependence on grating: RED

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

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

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

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

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

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

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)

Spectrometer Spatial Calibration in PV External 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

Spectrometer Spatial Calibration in PV Expected Herschel background level ~450 Jy at 77 micron (factor 6 less) ~ 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