PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm Post-Operations Calibration Goals E. Sturm

PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm One particular review board question: “All plans foresee refinements to calibrations, data products, and software. However, no performance or accuracy goals are given, making the entire process open-ended. There should be a clear definition of what constitutes "success" (or at least "good enough").”

PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm Overall goal: - push instrument uncertainties to a level below the uncertainties that come from the applied models More specifically: connect the (highly accurate) ground based NIR calibration scheme (based on stars) with the current best submm/mm calibration scheme (based on Uranus/Neptune) via the PACS measurements. To reach such a goal we have to analyse the photometer measurements of the fiducial stars, the prime asteroid calibrators and the planets Uranus/Neptune in a homogeneous way, investigate the various issues like non-linearity, cross-talk, colours, pointing,.... and compare it to the model predictions. This work will continue during the next years and progress/milestone will be given in regular calibration meetings and should also be reviewed in a dedicated calibration review during post-operations phase. Calibration goals

PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm Examples w.r.t. pre-flight requirements: -The internal photometric calibration (reproducibility) of the spectrometer has a goal tolerance of 3%. Particularly if this also implies that all spaxels (rather than just the central one) are that well calibrated with respect to each other we have not quite reached this. - The optical distortion of the photometer is supposed to be known to within 1/4 pixel (blue), i.e. 0.8arcsec. Given the pointing uncertainties in the process of measuring the distortion we are currently not sure about this Examples for requirements from users beyond what we have specified: -SgrA* time variability experiment, which asks for photometric stability that has never been specified, and unheard-of pointing measurement accuracy - the desire to detect very weak (1%) spectral features (narrow or broad) on a healthy continuum is not compatible with our 3% RSRF goal. Calibration goals

PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm - Flux calibration accuracy for point sources : we are working on a correction for instrumental contributions like the evaporator temperature and the mirror temperature. The prospects are that the flux stability is better than 1%, which is of course very useful for variability studies - even on large timescales. A direct application would be to study the still poorly investigated episodic nature of star formation activity. We are now clearly limited by the accuracy of the models. We already see systematic differences between the models of different spectral types. Altogether, beating down the intrinsic flux calibration uncertainties would also help providing a catalogue of high fidelity calibration objects that could be used for other FIR facilities (SPICA, ALMA).

PACS ICC Meeting #41 ESAC, 6/7 November 2012POP Calibration GoalsE. Sturm - stability of the PSF. If we can come up with a good characterisation of the influences that modify the PSF and maybe even provide a correction tool (pointing product?) to eliminate systematic effects, this would be very helpful to analyse marginally resolved features like filaments or circumstellar discs. We see recurring requests from the community for PSF fitting, subtraction or deconvolution tools.