PACS instrument and calibration web pages


This page provides up-to-date information, documents, reports, and links about the PACS instrument, from preparing observations, through reducing and calibrating PACS observations, to working with PACS maps and cubes.

You can also consult the PACS NHSC homepage.

Observing with PACS

  • The PACS Observer's Manual HTML PDF (11 Mb), version 2.3, 8-June-2011 : the first thing to read before applying for time with PACS (or even before working on PACS data for the first time), as it tells you how the instrument works. This includes:
    • A description of the layout and the components of the PACS photometer and spectrometer
    • A description of the scientific capabilities of the instrument: spectral response functions, sensitivity values, point spread functions, astrometric accuracy, flux calibration information
    • A description of the standard observing templates used to set up PACS observations; here you can also find the various acronyms that are used in the PACS data reduction guides
    • A brief description of PACS data products
  • AOT Release Notes: dedicated release notes per AOT (the astronomer's observing template, i.e. the observing time planning).
    • Information about how the various standard observing blocks work
    • Summaries of transmission functions, sensitivity, etc. for use in your observing planning (similar to what you will find in the Observer's Manual)
    • Here you can also find the various acronyms that are used elsewhere in PACS documentation
  • The PACS fact sheet
  • A collection of Key information of PACS is provided on the NHSC web site.

Although we are now in the post-operations phase of the mission, the PACS OM and the AOT release notes can still be useful to read for a background understanding on how PACS data were gathered

The In-flight scientific capabilities of the PACS instrument are also given in this paper: The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory (1.5 Mb), Poglitsch et al., 2010, A&A, 518, L2

PACS calibration and performance

Data processing known issues of standard products for photometry and spectroscopy: Bulk-processed Level 2/2.5 products are provided in the Herschel Science Archive. This Data Processing Known Issues page describes typical problems and caveats the observer needs to be familiar when looking at the results of this "SPG" (standard product generation) processing. 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.

Photometer calibration in scan maps

Photometer map-makers

  • Four fundamentally different map-makers are offered in HIPE 13 with interactive pipeline scripts, starting from Level 1. These map-makers are used in different ways to generate standard products ("SPG" product) provided by the Herschel Science Archive: high-pass filtering is applied to generate Level2 products, while Unimap and JScanam are used to create Level2.5 products. Level3 products are mosaics of Level2.5 products that belong to the same sky field and to the same observing program.
    • Highpass filtering branch, where the bolometer timelines are high-pass filtered to remove the 1/f noise, but at the expense of extended emission. It provides optimum sensitivity to point-sources
    • MADmap, a GLS (generalised least square) map-maker, that allows one to preserve extended emission at all scales. MADMap is not used anymore in the SPG processing, but it is still available as an interactive script.
    • Unimap, a light (memory-wise) GLS map-maker from Lorenzo Piazzo ('La Sapienza' University of Rome) under a free Matlab runtime environment, with advanced pre-processing (drift correction, jump detection) and post-processing stages (bright sources). The runUnimap task is used to invoke the Unimap Matlab routine on the users's computer.
    • JScanam, a Java-version of the IDL Scanamorphos map-maker, an IDL map-maker from Hélène Roussel (IAP) with an advanced and powerful destriper for PACS maps.
  • A report of the map-making working group compiled by Roberta Paladini is available: PACS map-making tools: analysis and benchmarking, 1 Nov. 2013.
  • An updated version of that report, concentrating on JScanam, MADmap and Unimap in their latest versions is available: PACS map-making tools: analysis and benchmarking, 30 March 2014.
  • If you are using data with SPG v 12 or reducing data with HIPE 12, remember that the optical field distortion in not applied at level 1. As a result, external map-makers starting from level 1 have a systematic flux overestimate of 6-7% in the red channel and a lower underestimate (~2%) in the blue channel of the flux scale.
  • Links:

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. (Please note, this document refers to the calibration status and performance of pipeline version v8.0. An update compatible with HIPE v13 release will be provided soon.) This includes:
    • flux calibration accuracies for chop nod and unchopped observations
    • the beam efficiencies and the PACS integral field footprint
    • spectral leakages and ghosts
    • wavelength calibration, including information on a skew our native line profile develops as a point source moves off the centre of a spaxel
    • table of the point source correction factors for different wavelengths
  • The calibration of the spectrometer is based on repeated measurements of planets, asteroids, and stars. The RMS scatter of these measurements are just over 10% within any spectral band, about the same when comparing different spaxels, and similar (but higher in the red) when looking for broad-band features within any band. See the PACS Spectrometer Calibration Document for the exact numbers. These calibration certainties are independent, and should be combined when quoting calibration errors.
  • An explanation of the data errors for any particular observation is provided in the PACS Data Reduction Guide for spectroscopy (sec. 7.6 in the HIPE 13 version of the document)
  • PACS spectrometer beams, version 3, can be downloaded here: PCalSpectrometer_Beam_v3.tar.gz. These beams are based on measurements of a raster with step size 2.5" around Neptune. These beam maps are useful e.g. if you want to compare to the flux distribution of your observation of a point source. Version 3 has the beam efficiencies for all IFU spaxels, and is a drastic improvement wrt version 2 as the spacecraft pointing was reconstructed more accurately. This reconstruction resulted in a non-equidistant sampling of the beam efficiency in the sky, but the beam products offered are equidistantly-sampled on a grid of 0.5 arcseconds. Each beam is normalised to the fitted peak value of the central spaxel. The WCS associated with the beam is in sky coordinates for position angle 0. The central part of the beam is the Gaussian fit to the measured beam efficiencies. This has been verified to be a very good description on the different raster observations we have of the central spaxels for wavelengths longer than 80 micron. Below 80 micron, the actual beam shows the square detector footprint, and the Gaussian approximation in the beam products v3 over-predicts the real beam efficiency by 1.5 to 2 percent. The outer part of the beams contains the interpolated values of the irregularly sampled measurements. Version 3 of the spectrometer beams are sharper than version 2, and shows the ghosts (ghosts are discussed in the Spectrometer Calibration Document ) more clearly, as well as the three-lobe structure of the Herschel telescope PSF.
  • The raw data from which the PACS spectrometer beams (all versions) have been derived is also available as tables (y, z offset - signal):
    • SpecSpatial_BeamEfficiency_central_spaxel_tables_v1.tar.gz:This contains a FITS file for each wavelength measured for the central spaxel only. Raw data of the coarse and fine rasters are combined. The array dimension of the fits file is [3,npoints] where the first column gives the y raster position, the 2nd column the z raster position and the 3rd column the normalised flux measured at this raster position.
    • SpecSpatial_BeamEfficiency_tables_v1.tar.gz: Raw measurements PACS beams - all spaxels, coarse raster measurements only: each fits files corresponds to one wavelength. Each file contains the data for all spaxels of the coarse raster measurement only. Each fits file holds an array of 3x25x25x25 where: (0,25,25,25)=y raster position, (1,25,25,25)=z raster position, (2,25,25,25)=flux normalized to the central spaxel. The second and third dimensions are the raster position indices (y and z) and the last dimension is the module number (=spaxel number).
  • Point source observations. To extract and calibrate the spectrum of a point source, it is necessary to use one of the tasks provided: it is not enough to add up the field-of-view of use the central spaxel only. How to do this is documented in the PACS DRG for spectroscopy.

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 further explained in the PDRGs. Clicking on 'Install' will install the latest calibration files.
  • The history of the calibration files that have been released to the community is provided here: PACS Calibration File History.
  • 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.

Reducing PACS data

A brief introduction to reducing PACS data in HIPE. You can consult the PACS Data Reduction Guides (photometry and spectroscopy; available via HIPE) for more detail.

  • PACS data are reduced with pipeline scripts which are a set of command-line tasks that process the data from Level 0 (raw) to Level 2/2.5 (science-ready). There is more than one flavour of pipeline script, tailored to different types of science target, AOT, and observing plan. These 'interactive' pipeline scripts are provided in HIPE and explained in the data reduction guides.
  • The data you get from the the HSA will have been processed by the 'SPG' (Standard Product Generator) using one pipeline script flavour per AOT. Which script is used is documented in the PDRG.
  • The SPG scripts include all the stable pipeline tasks within those scripts, with task settings that correspond to the most common type of science target for each AOT. But some pipeline tasks still can only be run via the interactive pipeline scripts, and to modify the parameter settings for the important pipeline tasks also requires you re-process the data. The Launch Pads (see below) include a guide to understanding the pipeline scripts and how to decide whether to reprocess your data and if so, with which script.

HIPE, data reduction documentation, and useful links for data issues

  • HIPE (Herschel Interactive Processing Environment) is the tool used to inspect, reduce, and analyse Herschel data. The latest User Release HCSS (Herschel common science system) version that you should use for reducing PACS data is HIPE v13.0 It can be downloaded from: In the CIB (continuous integration build) this version corresponds to Track 13, build 5130. The CIB is the continuously bug-fixed/upgraded/improved version of HIPE, which every few months (in the beginning of the mission) or yearly (in the post-operations phase) becomes a stable User Release.
  • Within HIPE you can access all the PACS data reduction documentation and the general HCSS and HIPE user documentation for Track 13 here. The documentation provided via HIPE opens in a web browser, but for those of you who prefer PDF, we include the PACS Data Reduction Guides as PDF files here (note that within the standalone pdf versions, external links will not work):
  • The what's new in HIPE 13 page lists the changes in HIPE version 13.x with respect to the 12.x series, and provides a detailed list of updated functionalities, product changes, and calibration aspects.
  • The Data products known issues page details issues about the pipelines or the data products that are known about and offers advice for dealing with them. Consult this if you encounter problems with your data to see if it has already been addressed.
  • Link to the General HCSS Public Twiki page (with general framework information and updates):

Cookbooks and interactive pipeline scripts

  • The various interactive pipeline scripts PACS photometry and spectroscopy provide in HIPE can be seen as cookbooks, since they take you through each pipeline, task by task, explaining briefly what each task does, commenting on the more crucial pipeline tasks, and showing you how to plot, image, visualise and inspect your data as you work through the pipeline. An example public observation is included with each so you can test it out before using it on your data. These data reduction scripts are available in HIPE under the menu: Pipeline --> PACS --> Photometer/Spectrometer.
  • The PACS Launch Pad from HIPE 13 for photometry is provided here. The PACS Launch Pad from HIPE 13 for spectroscopy is provided here. These are taken from the first chapters of the respective PDRGs and are a useful quick-start guide to loading your data into HIPE, looking at them, and then what to know and do before you begin reprocessing your data with one of the pipelines. Also included is
    • why we recommend you do re-pipeline your data
    • what you need to pay attention to for different types of astronomical source
    • what the crucial pipeline tasks are
    • what the post-pipeline processing tasks that we provide are

Tutorials and scripts

  • The Scripts menu in HIPE takes you to a set of PACS photometry and spectroscopy useful scripts. In HIPE 13 these are:
    • Point source aperture photometry
    • Multiple point source aperture photometry
    • Image convolution (photometry)
    • Combine PACS and SPIRE point source spectra
    • Point source corrections: for a source located in the central spaxel of the field-of-view, and for a source located elsewhere
    • Post-processing tasks for extended sources
    • Off subtraction and post-processing for unchopped range spectroscopy
    • Fitting mapping observations: for mosaic cubes and on the pre-mosaic cubes
    • Fitting single pointing cubes
    • Re-creating the standalone browse products
    • Convolution for spectral images
  • See the various walkthroughs on the NHSC PACS page.
  • The Nasa Herschel Science center (NHSC) has also posted some PACS Data Processing Tutorials.
  • HIPE Academy on YouTube: here you can find recordings of various seminars and webinars that the HSC have given on working in HIPE, reducing Herschel data, using various tools to visualise and manipulate data in HIPE, and etc.

Quick links: wavelengths, sensitivity, PSFs

A summary of instrumental and calibration details that a data-reducing astronomer often wants know.


  • Wavelength ranges, resolution, band names
    • The blue bands are B2A (blue, second order) and B2B (green, second order), and B3A (blue, third order), and in the red we have R1 (first order)
    • The wavelength ranges and resolutions can be found in table 4.1 of the (PACS Observer's Manual) * Spectral leaks: there is order leakage in our filters that affects the ends of the blue and red bands. These are documented as figures in sec. 4.1 of the PACS Spectrometer Calibration Document and again in sec. 4.8 of the PACS Observer's Manual . How to deal with the red leakage by reducing the data with a particular calibration file is documented in the PACS spectrometer data reduction guide (secs 5.3 and 6.4 in the HIPE 13 version).
  • Second-pass spectral ghosts: see sec. 4.2 of the PACS Spectrometer Calibration Document to learn about ghosts. These are bright spectral lines at one wavelength "echoing" to another wavelength in another spaxel. This is also documented in sec. 4.9 of the PACS Observer's Manual * The footprint of the integral field unit: text and figures showing the footprint of the PACS IFU, and how that compares to the beam, can be found in the PACS Spectrometer Calibration Document (sec. 3) where you will also find information about the beam maps (at high spatial resolution and for various wavelengths), beam efficiencies, and the point source loss corrections. The same information can be found in the PACS Observer's Manual (sec. 4.6).
  • The FWHM of a point source (i.e. of the beam): this information can be found in fig. 4.12 of the PACS Observer's Manual and again in the PACS Spectrometer Calibration Document
  • Spectral line profile skews for off-centred sources: point sources that are not centrally located in a spaxel will show a skew to their spectral lines. The effect of this is to move the peak wavelength and slightly change the measured FWHM. Some calibration of this has been done and this can be found in sec. 4.7.2 and 4.7.3 of the PACS Observer's Manual and sec. 5.2 of the PACS Spectrometer Calibration Document.
  • Calibration certainties: these are all documented in the beginning of the PACS Spectrometer Calibration Document. Data errors are discussed in the PACS DRG for spectroscopy (sec. 7.6 in the HIPE 13 version).
  • Expected signal-to-noise ratios and line sensitivity: this depends on the AOT, this information is also provided in the AOT Release Notes (see also update in sec. 6.1.3 of the PACS Observer's Manual) and can also be computed by running HSPOT.


  • Filters and bands
    • The blue and green bands are not observed simultaneously, the red is observed simultaneously with each. Transmission functions can be found in the PACS Observer's Manual sec. 3.2.
  • PSF and beams: the beams maps are provided as FITS files, and information about then can be found in the section 'Photometer calibration in scan maps'
  • Point source photometry
    • Colour corrections: these are provided on this page in the section 'Photometer calibration in scan maps'
    • Aperture corrections/EEFs (encircled energy fractions) are provided in sec. 8 of the PACS Photometer Point Spread function document
  • Effects of nonlinearity, saturation, stray light, crosstalk and ghosts: can be found in sec. 6 of the PACS Photometer Point Spread function document
  • Calibration certainty: is discussed on this page in the section 'Photometer calibration in scan maps'), with links there to two publications. You can also read sec 3.3 of the PACS Observer's Manual
  • Sensitivity: this depends on the AOT, this information is also provided in the AOT Release Notes, and can also be computed by running HSPOT.

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pdfpdf aa14535-10.pdf manage 1571.0 K 04 Nov 2010 - 16:23 BrunoAltieri  
pdfpdf bolopsfv1.01.pdf manage 5658.9 K 05 Nov 2010 - 16:27 BrunoAltieri  
pdfpdf PACSPSF_PICC-ME-TN-029_v2.0.pdf manage 3171.5 K 05 Nov 2010 - 16:28 BrunoAltieri  
pdfpdf SimulPSP_v1.0.pdf manage 5323.7 K 15 Nov 2010 - 11:16 BrunoAltieri  
pdfpdf ExtSrcPhotom.pdf manage 3303.5 K 12 Apr 2011 - 18:26 BrunoAltieri  
pdfpdf PICC-NHSC-TN-029.pdf manage 975.7 K 12 Apr 2011 - 18:30 BrunoAltieri  
pdfpdf cc_report_v1.pdf manage 2578.7 K 12 Apr 2011 - 18:30 BrunoAltieri  
pdfpdf pacs_bolo_fluxcal_report_v1.pdf manage 3122.3 K 12 Apr 2011 - 19:40 BrunoAltieri  
pdfpdf PacsSpectroscopyPerformanceAndCalibration_31May2011.pdf manage 2329.4 K 02 Jun 2011 - 13:28 JeanMatagne  
pdfpdf PhotMiniScan_ReleaseNote_20101112.pdf manage 1988.8 K 06 Jun 2011 - 17:05 BrunoAltieri  
pdfpdf PDRG_Jun2011.pdf manage 5346.0 K 07 Jun 2011 - 22:27 KatrinaExter PDRG Jun 2011
pdfpdf PPR_Jun2011.pdf manage 4338.0 K 07 Jun 2011 - 22:33 KatrinaExter PPR Jun 2011
pdfpdf PacsSpectroscopyPerformanceAndCalibration_v2_4.pdf manage 2056.7 K 17 Jun 2011 - 10:27 BartVandenbussche PACS spectrometer performance and calibration document, v2.4
elsegz PCalSpectrometer_Beam_v1.tar.gz manage 85.7 K 14 Jul 2011 - 23:08 BartVandenbussche PACS Spectrometer beams
pdfpdf PACS_LaunchPads_Dec2011.pdf manage 116.3 K 06 Dec 2011 - 09:05 KatrinaExter PACS launch pads from PDRG of Nov 11
pdfpdf PDRG_Dec2011.pdf manage 6655.5 K 07 Dec 2011 - 10:05 KatrinaExter PDRG Track 8.0 RC6
elsegz PCalSpectrometer_Beam_v2.tar.gz manage 930.7 K 16 Jan 2012 - 12:49 BartVandenbussche PACS spectrometer beam effiencies, version 2
pdfpdf bolopsf_20.pdf manage 9635.3 K 10 Apr 2012 - 16:40 BrunoAltieri PACS photometer point spread function, v2.0
pdfpdf PDRG_Spec_May12.pdf manage 2494.9 K 25 May 2012 - 14:10 KatrinaExter PDRG Spectroscopy from May 2012
pdfpdf PDRG_Phot_May12.pdf manage 471.2 K 25 May 2012 - 14:24 KatrinaExter PDRG Photometry for May 2012
pdfpdf PACS_LaunchPads_May2012_P.pdf manage 111.0 K 25 May 2012 - 14:28 KatrinaExter Photometry
pdfpdf PACS_LaunchPads_May2012_S.pdf manage 137.7 K 25 May 2012 - 14:28 KatrinaExter Spectroscopy
pdfpdf hpf_psf_tn_final.pdf manage 6492.6 K 14 Nov 2012 - 18:06 BrunoAltieri Effect of high-pass filtering
pdfpdf pacs_spec.pdf manage 2864.4 K 22 Jan 2013 - 15:13 BrunoAltieri pacs sepctrometer PDRG Hipe 10
pdfpdf pacs_phot.pdf manage 4670.2 K 22 Jan 2013 - 15:13 BrunoAltieri PACS photometer PDRG Hipe 10
elsegz PCalSpectrometer_Beam_v3.tar.gz manage 17278.3 K 05 Mar 2013 - 15:06 BartVandenbussche PACS spectrometer beam efficiencies v3
elsegz SpecSpatial_BeamEfficiency_central_spaxel_tables_v1.tar.gz manage 120.9 K 08 Mar 2013 - 17:41 BartVandenbussche Raw measurements PACS beams - central spaxel only
elsegz SpecSpatial_BeamEfficiency_tables_v1.tar.gz manage 2742.3 K 08 Mar 2013 - 17:43 BartVandenbussche Raw measurements PACS beams - all spaxels
pdfpdf PICC-CR-TN-044.pdf manage 294.2 K 09 May 2013 - 15:01 BrunoAltieri The bandwidth of the PACS photometric system
pdfpdf PACS_LaunchPads_Jun2013_S.pdf manage 169.8 K 07 Jun 2013 - 13:12 KatrinaExter pacs spec launch page jun 2013
pdfpdf pacs_phot_June2013.pdf manage 5138.2 K 29 Jul 2013 - 09:25 BrunoAltieri PACS photometer PDRG Hipe 11
pdfpdf PACS_Spec_DRG_0613b.pdf manage 3112.5 K 30 Sep 2013 - 10:25 KatrinaExter PACS spec DRG track 11
pdfpdf pacs_mapmaking_report_ex_sum_v3.pdf manage 9781.5 K 04 Nov 2013 - 23:49 BrunoAltieri mapmaking report
pdfpdf balog_PACS_Phot_ADS.pdf manage 432.5 K 04 Nov 2013 - 23:50 BrunoAltieri Balog exp. astr. paper 2013
pdfpdf ExpAstr_PrimeAsteroids_revision1.pdf manage 928.3 K 04 Nov 2013 - 23:51 BrunoAltieri Mueller exp. astr. paper 2013
pdfpdf Nielbock_ExpAstr_2013.pdf manage 1464.5 K 11 Mar 2014 - 16:19 BrunoAltieri Nielbock et al., 2013, Experimental Astronomy
pdfpdf Mueller_ExpAstr_2013.pdf manage 1512.3 K 11 Mar 2014 - 17:39 BrunoAltieri Mueller et al., 2013, Experimental Astronomy
pdfpdf Balog_ExpAstr_2013.pdf manage 566.4 K 11 Mar 2014 - 17:39 BrunoAltieri Balog et al., 2013, Experimental Astronomy
pdfpdf pacs_phot_Hipe12.pdf manage 5134.1 K 17 Mar 2014 - 17:50 BrunoAltieri PACS Data Redction Guide for Hipe 12
pdfpdf pacs_spec_Hipe12.pdf manage 2545.7 K 18 Mar 2014 - 08:59 ElenaPuga PACS Spectrometer Data Reduction Guide for Hipe 12
elsegz PCalSpectrometer_Beam_v4.tar.gz manage 13984.5 K 22 May 2014 - 16:23 BartVandenbussche PACS spectrometer beam efficiencies v4
elsegz PCalSpectrometer_Beam_v5.tar.gz manage 17293.7 K 28 May 2014 - 14:42 BartVandenbussche PACS spectrometer beam efficiencies v5
pdfpdf pacs_mapmaking_report14_v2.pdf manage 2811.1 K 29 Jul 2014 - 23:48 BrunoAltieri PACS Map-making Tools: Update on Analysis and Benchmarking
pdfpdf pacs_phot_Hipe13.pdf manage 5136.2 K 09 Apr 2015 - 13:16 KatrinaExter  
pdfpdf pacs_spec_Hipe13.pdf manage 2333.4 K 09 Apr 2015 - 13:17 KatrinaExter  
pdfpdf pacs_photLP_Hipe13.pdf manage 4729.2 K 09 Apr 2015 - 13:28 KatrinaExter  
pdfpdf pacs_specLP_Hipe13.pdf manage 1576.5 K 09 Apr 2015 - 13:28 KatrinaExter  
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