1 Markus Nielbock (MPIA) – PACS Calibration Status Report Herschel Calibration Steering Group Meeting #24 PACS Calibration Status Report Markus Nielbock (MPIA Heidelberg) on behalf of the PACS Calibration Working Group RAL, Didcot, 3 rd February 2010

2 Outline Markus Nielbock (MPIA) – PACS Calibration Status Report ● wrap-up remainder of PACS PV phase (update since HCalSG #23) ● selected recent analysis results crucial for calibration ● AOT release status ● status Routine Phase Calibration Plan General and detailed status of PACS: see presentation A. Poglitsch, SDP Workshop, December 2009

3 Wrap up of PACS PV Phase Calibration Markus Nielbock (MPIA) – PACS Calibration Status Report ● 14 additional ODs between OD 160 and OD 200 ● OD 161 contained pointing stabilisation monitoring after STR switch/dump ● OD 194/195 additionally assigned to PACS ● OD 200 contained STR interlacing pointing test

4 PACS Photometer Flux Calibration Markus Nielbock (MPIA) – PACS Calibration Status Report ● systematic flux calibration verification on all suitable observations ● Chopped point source AOT: ● 67 AORs high gain ● 25 AORs low gain ● Scan map AOT: ● 89 AORs high gain, medium scan speed (default) ● 15 AORs high gain, other scan speeds ● 4 AORs low gain (Neptune) ● primary and secondary flux standard stars, asteroids, planets ● Models of L. Decin (stars), R. Moreno (planets), T. Müller (asteroids)

5 PACS Photometer Flux Calibration Chop-Nod PS AOT results (preliminary) Markus Nielbock (MPIA) – PACS Calibration Status Report Δ stars  asteroids □ planets

6 PACS Photometer Flux Calibration Chop-Nod PS AOT results (preliminary) Markus Nielbock (MPIA) – PACS Calibration Status Report ● general good agreement between the different object classes ● stars and asteroids agree within ±10% ● no indication for NIR leak (stars are about 1000 times brighter in ● the NIR than the asteroids) ● linear relationship for almost the entire flux range ● only Neptune seems to have lost a few percent ● (crosstalk? non-linearity effect?) blu e gree n re d ● photometry consistent for differing aperture radii after applying ● aperture correction (> 100 mJy blue + green, > 500 mJy red) ● based on ~30 PS AOT observations (high gain, calTree V3): ● Obs/Mod = 1.05 ± 0.07, 1.08 ± 0.05, 1.28 ± 0.07

7 PACS Photometer Flux Calibration Scan Map AOT results (preliminary) Markus Nielbock (MPIA) – PACS Calibration Status Report ● Mad Map gives wrong fluxes in cases of multiple repetitions ● proper masking in high-pass filtering is necessary for the brightest targets ● “blind” high pass filtering affects the final flux level by typically 5-40% ● the Neptune observations produce positive and negative “ghosts” ● scan maps look much better and the background is much smoother ● (proper noise analysis pending) ● In the red band there is a negative ghost image at a distance of 52”/104” with an integrated ● flux of about 4% of the main source.  cross talk? blu e gree n re d ● flux verification in progress

8 PACS AOT Release Status Photometer Markus Nielbock (MPIA) – PACS Calibration Status Report Scan map AOT released on 6 th October 2009 ● improved homogeneous map coverage (scan leg separation, rotation angle) ● preferred scan speed: 20”/s ● reduced scan leg turnover idle times Chopped point source AOT released on 12 th November 2009 ● first readout of each chopper plateau has to be discarded ● alternative point source scan map proposed ● latest design: 10 scan legs, 4” scan leg separation, 2.5' scan leg length ● two maps with instrument position angles 70 and 110 degrees ● coverage improved for aperture photometry ● take 650 s without initial slew

9 PACS AOT Release Status Spectrometer Markus Nielbock (MPIA) – PACS Calibration Status Report Chopped line spectroscopy for single pointing released on 6 th November 2009 ● optimised/increased dynamic range by switching of integrating capacities ● pointing test to assess quality/accuracy improvements by STR interlacing in progress Wave switching line spectroscopy released on 3 rd December 2009 ● optimised/increased dynamic range by switching of integrating capacities Chopped range spectroscopy / SED mode partially released on 18 th January 2010 ● optimised/increased dynamic range by switching of integrating capacities (SED mode) ● tests to improve symmetry of chop-nod patterns to reduce transients in progress ● spectral dithering for SED mode in progress ● HSPOT update needed to fully implement the upgrade Unchopped spectroscopy not to be released before end of March

10 PACS Routine Phase Calibration Plan Markus Nielbock (MPIA) – PACS Calibration Status Report ● latest version released: 0.25, 28 th January 2010 ● issue 0.3 in progress ● baseline for cycle 2 to 8 Routine Phase Calibration deliveries

11 PACS Routine Phase Calibration Plan Major Items Markus Nielbock (MPIA) – PACS Calibration Status Report Observations deferred from PV phase – 5h ● mostly photometer flux measurements of sources not visible during PV phase ● completed (except for β And, a prime flux calibrator suspected to have IR excess) Long term reproducibility and stability – 421h ● to check photometer flux calibration aspects in regular intervals (2 weeks – 6 months) ● to check spectrometer flux and wavelength calibration in regular intervals ● (2 weeks – 6 months) Long term trends – 30h ● to monitor detector effects covered by orbit prologue measurements and internal ● calibration blocks at the beginning of each AOR execution ● to monitor telescope background introduced by seasonal effects (complementing the ● assessment during the initial cool-down in CoP)

12 PACS Routine Phase Calibration Plan Major Items Markus Nielbock (MPIA) – PACS Calibration Status Report Extension of PV phase and new programmes – >87h ● additional spectrometer wavelength calibration ● further AOT validation ● dedicated SPIRE/PACS Parallel Mode flux calibration ● additional pointing verification/calibration (STR temperature, interlacing) for photometer ● and spectrometer (OD 274, 276 pointing verification programmes) Check for aging effects and re-calibration programmes ● due to aging of instrument components or space environment changes ● not yet considered

13 PACS Routine Phase Calibration Plan Time Budget Markus Nielbock (MPIA) – PACS Calibration Status Report Duration Routine Phase: 3 years Operations per OD: 21 hours Assumed calibration budget for 3 instruments:1/7 of RP Resulting calibration budget for PACS: 1095 hours (1278 hours for 3.5 years) Currently requested time for PACS: ~550 hours (50%) An additional margin must be reserved for unexpected events and refinement of PV phase calibration, if needed.