PACS Calibration Status Report Herschel Calibration Steering Group Meeting #28 PACS Calibration Status Report Markus Nielbock (MPIA Heidelberg) on behalf of the PACS Calibration Working Group Markus Nielbock (MPIA) – PACS Calibration Status Report ESTEC, Noordwijk, 13th April 2011

Outline wrap-up PACS calibration programme implementation new PACS PHOT flux calibration non-linearity calibration PACS PHOT PACS SPEC SED/flux calibration PACS PHOT/SPEC cross calibration Markus Nielbock (MPIA) – PACS Calibration Status Report

Wrap-up of PACS RSP Calibration full description and details in: PICC-MA-PL-002 up to cycle 38: 1398 AORs, 469.0 h PACS Photo PACS Spectro SPIRE/PACS Parallel Engineering 829 AORs 528 AORs 20 AORs 21 AORs 157.3 h 295.5 h 15.7 h 0.4 h Markus Nielbock (MPIA) – PACS Calibration Status Report anticipated calibration time needed: 832.5 h

PACS Photometer Flux Calibration New calibration scheme (1) full description in: PICC-ME-TN-037 was based on point source aperture photometry of chopped observations measured from Vesta sky set to zero at r = 60” combination of Vesta and Mars sky set to zero at r = 600” adds ~10% flux at large radii Markus Nielbock (MPIA) – PACS Calibration Status Report scan map now dominant observing mode (small offset in flux to chopped)

PACS Photometer Flux Calibration New calibration scheme (2) resulting correction based on the five most reliable calibrators: will be included in the next HCSS 7.0 release Markus Nielbock (MPIA) – PACS Calibration Status Report together with aperture correction task resulting absolute PACS PHOT flux calibration accuracy (incl. model accuracy): PACS 70 µm: 2.64% PACS 100 µm: 2.75% PACS 160 µm: 4.15%

PACS Photometer Flux Calibration New calibration scheme (3) Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Photometer Flux Calibration New calibration scheme (4) Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Photometer Flux Calibration Colour correction tables update full description in: PICC-ME-TN-038 calculated for standard and modified Black Bodies tables allow for translation to neighbouring bands of other instruments (e.g. IRAS, ISO) Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Photometer Flux Calibration Non-linearity investigation non-linearity range begins at approx. 100 Jy per point source flux coverage in calibration programme insufficient extension of calibrator list with bright asteroids (flux changes with time) repeated observation at different epochs to obtain good sampling across crucial flux range 10 Hygiea 4 Vesta 1 Ceres Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Spectrometer Flux Calibration Latest progress – internal calibration block (1) ground based total flux calibration now complemented with internal calibration block slight improvement of total flux uncertainty overall flux calibration uncertainty: ~20-30% 20 24 15 19 10 12 14 5 9 4 PACS-S IFU Markus Nielbock (MPIA) – PACS Calibration Status Report rms = 12.1% rms = 10.9% ground calibration + scaling from in-flight calibration response correction from internal calibration block

PACS Spectrometer Flux Calibration Latest progress – internal calibration block (2) ground calibration + scaling from in-flight calibration response correction from internal calibration block good pointing Markus Nielbock (MPIA) – PACS Calibration Status Report bad pointing pointing jitter is the dominating contribution to remaining uncertainty

PACS Spectrometer Flux Calibration Work in progress – correction of pointing jitter induced flux uncertainty (1) applicable to moderately bright point sources only Basic idea: Use reference observation of bright point source (e.g. Neptune) as proxy for flux scaling factor to correct for missing flux in central IFU module. Requirement: Sufficiently large database of reference observations to determine the flux distribution for optimal pointing performance. Example: HD 161796 (34 observations) Markus Nielbock (MPIA) – PACS Calibration Status Report division by mean of all 34 observations correction with internal calibration block correction for pointing jitter both corrections combined

PACS Spectrometer Flux Calibration Work in progress – correction of pointing jitter induced flux uncertainty (2) current calibration internal calibration block + pointing jitter correction Markus Nielbock (MPIA) – PACS Calibration Status Report additional observations needed to complement reference observation database 25x25 rasters on Neptune at six different reference wavelengths planned for cycle 38 not applicable to extended and faint sources → CP raster pointing mode (?)

ground based optical/NIR PACS Cross Calibration SED spectroscopy (1) well characterised Herbig Ae/Be star observed with PACS spectrometer spectral response calibrated with background normalisation method ground based optical/NIR mainly SPITZER Markus Nielbock (MPIA) – PACS Calibration Status Report photospheric model SPITZER SPITZER IRAS + AKARI PACS

PACS Cross Calibration SED spectroscopy (2) background spectrum derived from Neptune observation Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Cross Calibration SED spectroscopy (3) background spectrum derived from Pallas observation additional PACS photometer observations planned for cycle 39 for cross calibration Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Calibration Summary and outlook PACS photometer calibration in good shape non-linearity calibration to be added soon PACS spectrometer flux calibration needs more attention pointing performance limits calibration accuracy (RSRF, central module flux, line shape) several data processing approaches to improve situation implementation of new AOTs (unchopped spectroscopy) bright line mode made available testing of CP raster pointing mode to improve nodding performance Markus Nielbock (MPIA) – PACS Calibration Status Report

PACS Markus Nielbock (MPIA) – PACS Calibration Status Report