TWiki> Public Web>PacsCalibrationWeb (revision 69)EditAttach

PACS instrument and calibration web pages

Introduction

This page provides up-to-date information about using the PACS instrument: from preparing observations to reducing your data. This page also provides you with the latest calibration accuracies and known PACS calibration issues.

Observing with PACS

  • AOT Release Notes: dedicated release notes per AOT (the astronomer's observing template, i.e. planning your observing time). These contain information about how the standard observing blocks work, transmission functions, sensitivity, etc.

Reducing PACS data

  • HIPE (Herschel Interactive Processing Environment): The latest User Release HCSS version that you should use for reducing PACS data is HIPE v8.2.0 It can be downloaded from: http://herschel.esac.esa.int/HIPE_download.shtml. In the CIB (continuous integration build) this version corresponds to Track 9, build 2824.

  • Within HIPE you can access all the PACS data reduction and HIPE-use documentation for Track 9. The PACS Data Reduction Guide has been split into two: Spectroscopy (here) and Photometry (here). The links are the PDRF versions from Track 9. (Note that within the standalone version, external links will go nowhere.) The PDRG follows the pipeline scripts (see "Cookbooks" below) and also explains what you are doing as you pipeline process.

  • The what's new in HIPE 9 page lists the changes in HIPE version 9.0 with respect to the 8.x series, provides a detailed lists of updated functionalities and calibration aspects.

Cookbooks

  • Our version of cookbooks are the pipeline scripts, because (i) we recommend you rereduce your data in any case and (ii) these scripts are heavily commented to guide you through the data reduction process. These data reduction scripts are available in HIPE under the menu: Pipeline --> PACS --> Photometer/Spectrometer.
  • See also the walkthroughs on the NHSC PACS page.
  • The PACS Launch Pads from May 2012 are provided for spectroscopy and photometry. These are taken from the first chapter of the PDRGs and are a useful quick-start guide to loading your data into HIPE, and then what to know and do before you begin reprocessing your data with one of the pipelines.

PACS calibration file versions

  • When starting HIPE, you will be informed if new calibration files are available. Clicking on 'show details' will show you the release note of the new calibration set, with details about the changes. This is all also explained in the PDRG (chap 2)

  • You can inspect the release notes for the calibration sets installed on your machine from within HIPE. Open the Calibration Sets View from the menu Window -> Show Views -> Workbench.

PACS calibration and performance

Photometer calibration in scan maps.

  • Herschel/PACS modelled point spread functions (3.1 Mb) is a related document presenting Zemax modelled point spread functions for both an `ideal' and an 'as built' Herschel telescope model. Tarballs with corresponding broad-band and monochromatic PSFs for these two cases are at http://pacs.ster.kuleuven.ac.be/pubtool/PSF. These are useful in addition to the observed PSFs but cannot replace them, since the models do not capture all effects found in the observed PSFs.

  • Point-source photometry: PACS uses 5 stars as primary calibrators with fluxes ranging from 0.6 to 15 Jy, plus fainter stars and asteroids as secondary calibrators. A new responsivity calibration (version) is deployed on the HCSS 7 track (this is explained in the internal report PICC-ME-TN-033 v1.01, where the associated encircled energy fraction [EEF] is given). This improves the accuracy of photometry to 3% in the blue channel and 5% in the red channel. The new calibration is described in detail in the technical note "PACS photometer point-source flux calibration (3.1 Mb) (PICC-ME-TN-037), version 1.0, 12 April 2011.

  • Point-source observations:
    • We refer to: PACS Photometer: chop/nod point-source & mini-scan map AOT release note: (2 Mb) version 2.0, 12 November 2010. We recommend you use the mini scan-map technique in all science cases related to point-sources, compact sources and also in cases of faint extended emission around point-sources. The chop/nod mode is no longer recommended for use.
    • However, for a technical assessment of the original chop/nod mode sensitivity intended for point-sources, we refer to SAp-PACS-MS-0711-09 (5.5 Mb).

PACS spectrometer calibration

  • PACS Spectrometer performance and calibration: The PACS Spectrometer Calibration Document v2.4 (16-June-2011) provides details on the calibration accuracy and the necessary information to optimally interpret PACS spectroscopy observations. New issues of this document will be released with new versions of the pipeline and new versions of the calibration tree provided in the Herschel interactive data analysis system.

  • Data processing known issues of standard products: Browse quality Level 2 products are provided in the Herschel Science Archive. This summary page describes typical problems and caveats the observer needs to be familiar when looking at these preview products. Aspects of product quality which can be further optimised by interactive processing are also summarised here. The document refers to the version of data processing pipeline currently being used for processing of incoming Herschel data (version number provided therein).

  • PACS spectrometer beams, version 2,can be downloaded here: PCalSpectrometer_Beam_v2.tar.gz. These were measured performing a raster with step size 2.5" around Neptune. These beams are useful to compare the flux seen in the different IFU spaxels with with a point source, or a certain brightness distribution in the sky. Version 2 has the beam effiencies for all IFU spaxels. Each beam is normalised to the fitted peak value. The WCS associated with the beam is in sky coordinates for position angle 0.

Planned processing and calibration improvements

  • The PACS ICC and the HSC calibration scientist teams are currently working on making the following processing and calibration improvements available to the users:
    • Making spectrometer convolution kernels available. These products will be useful to estimate line-ratios in oversampled spectral maps.
    • Improved hyperspectral cube reconstruction. A new algorithm including spatial upsampling and a drizzling layer will be provided for a better (i.e. sharper) spatial reconstruction of oversampled spectral maps. It will also take advantage of the updated spatial calibration product where each individual pixels has its own astrometry.
    • Improved a-posteriori pointing reconstruction based on guide star positions used for the observation.
    • Point source flux correction for observations not perfectly centered on the central spaxel.
    • Improved post-pipeline flatfield to correct small residual pixel-pixel response variations, which introduces a fringe-like pattern in spectra.
    • Improved transient and response drift correction for unchopped observations.
    • Improved correction for systematics affecting the spectral shape of sources and detectability of unresolved lines.
  • Planned changes to the non-PACS-specific functionality in HIPE are to be listed in What's new in HIPE 9.

Interest Groups and Scripts

Links

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf ExtSrcPhotom.pdf r1 manage 3303.5 K 2011-04-12 - 18:26 BrunoAltieri  
PDFpdf PACSPSF_PICC-ME-TN-029_v2.0.pdf r1 manage 3171.5 K 2010-11-05 - 16:28 BrunoAltieri  
PDFpdf PACS_LaunchPads_Dec2011.pdf r1 manage 116.3 K 2011-12-06 - 09:05 KatrinaExter PACS launch pads from PDRG of Nov 11
PDFpdf PACS_LaunchPads_May2012_P.pdf r1 manage 111.0 K 2012-05-25 - 14:28 KatrinaExter Photometry
PDFpdf PACS_LaunchPads_May2012_S.pdf r1 manage 137.7 K 2012-05-25 - 14:28 KatrinaExter Spectroscopy
Unknown file formatgz PCalSpectrometer_Beam_v1.tar.gz r1 manage 85.7 K 2011-07-14 - 23:08 BartVandenbussche PACS Spectrometer beams
Unknown file formatgz PCalSpectrometer_Beam_v2.tar.gz r1 manage 930.7 K 2012-01-16 - 12:49 BartVandenbussche PACS spectrometer beam effiencies, version 2
PDFpdf PDRG_Dec2011.pdf r1 manage 6655.5 K 2011-12-07 - 10:05 KatrinaExter PDRG Track 8.0 RC6
PDFpdf PDRG_Jun2011.pdf r1 manage 5346.0 K 2011-06-07 - 22:27 KatrinaExter PDRG Jun 2011
PDFpdf PDRG_Phot_May12.pdf r1 manage 471.2 K 2012-05-25 - 14:24 KatrinaExter PDRG Photometry for May 2012
PDFpdf PDRG_Spec_May12.pdf r1 manage 2494.9 K 2012-05-25 - 14:10 KatrinaExter PDRG Spectroscopy from May 2012
PDFpdf PICC-NHSC-TN-029.pdf r1 manage 975.7 K 2011-04-12 - 18:30 BrunoAltieri  
PDFpdf PPR_Jun2011.pdf r1 manage 4338.0 K 2011-06-07 - 22:33 KatrinaExter PPR Jun 2011
PDFpdf PacsSpectroscopyPerformanceAndCalibration_31May2011.pdf r1 manage 2329.4 K 2011-06-02 - 13:28 JeanMatagne  
PDFpdf PacsSpectroscopyPerformanceAndCalibration_v2_4.pdf r1 manage 2056.7 K 2011-06-17 - 10:27 BartVandenbussche PACS spectrometer performance and calibration document, v2.4
PDFpdf PhotMiniScan_ReleaseNote_20101112.pdf r1 manage 1988.8 K 2011-06-06 - 17:05 BrunoAltieri  
PDFpdf SimulPSP_v1.0.pdf r1 manage 5323.7 K 2010-11-15 - 11:16 BrunoAltieri  
PDFpdf aa14535-10.pdf r1 manage 1571.0 K 2010-11-04 - 16:23 BrunoAltieri  
PDFpdf bolopsf_20.pdf r1 manage 9635.3 K 2012-04-10 - 16:40 BrunoAltieri PACS photometer point spread function, v2.0
PDFpdf bolopsfv1.01.pdf r1 manage 5658.9 K 2010-11-05 - 16:27 BrunoAltieri  
PDFpdf cc_report_v1.pdf r1 manage 2578.7 K 2011-04-12 - 18:30 BrunoAltieri  
PDFpdf pacs_bolo_fluxcal_report_v1.pdf r1 manage 3122.3 K 2011-04-12 - 19:40 BrunoAltieri  
Edit | Attach | Watch | Print version | History: r162 | r71 < r70 < r69 < r68 | Backlinks | Raw View | Raw edit | More topic actions...
Topic revision: r69 - 2012-05-25 - KatrinaExter
 
This site is powered by the TWiki collaboration platform Powered by Perl