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PACS instrument and calibration web pages

Introduction

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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.
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This page provides up-to-date information about using the PACS instrument: from preparing observations to reducing your data. We include information summaries, technical reports, information about and links to HIPE--the data processing environment for Herschel data--and the PACS data reduction guides, and cookbooks and scripts that you can use in HIPE when working with PACS data. This page also provides you with the latest calibration accuracies and known PACS calibration issues, and information about what future calibration and processing improvements can be expected.
 

Observing with PACS

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  • 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.
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  • 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 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; these can also be found in the AOT release notes
    • A description of the standard observing templates that were used to set up PACS observations; here you can also learn the lingo that is used in the PACS data reduction guides (DRGs)
    • A brief description of PACS data products; though much more detail on this is provided in the PACS DRGs

  • AOT Release Notes: dedicated release notes per AOT (the astronomer's observing template, i.e. planning your observing time).
    • Information about how the various standard observing blocks work
    • Summaries of transmission functions, sensitivity, etc. for use in your observing planning
    • We are now at the end of the mission. But these release notes can still be useful to read for a background understanding on how PACS data were gathered--this dictates what you will see as you look at your PACS data while pipeline processing them
    • You can also learn here the lingo that is used in the PACS DRGs when describing the data reduction pipeline scripts
 
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Reducing PACS data

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Brief explanation

A brief introduction to reducing PACS data in HIPE. You can consult the PACS Data Reduction Guides (photometry and spectroscopy) for more detail.
  • The data you get from the the HSA will have been processed by the "SPG" (Standard Product Generator), which is another way of saying that it is processed with a tailored version of the latest pipeline scripts from the User Release. So, when HIPE User Release 11.0 is released, soon after all the Herschel data are processed with the SPG pipeline scripts of version 11.0, and so on for each User Release.
  • For PACS these SPG scripts are a copy of one flavour of interactive pipeline scripts. The SPG scripts include all the stable pipeline tasks with settings that correspond to the most common type of science target and observing plan (AOT). But some pipeline tasks can only be run via the interactive scripts. The Launch Pads (see below) of the data reduction guides brings you up-to-date on this matter.
  • This makes the SPG results a good starting point to look at your PACS data, but in most cases you can improve the results at least somewhat by reducing the data yourself.
  • For photometry and spectroscopy both there is more than one flavour of pipeline script, tailored to different types of science target or observing plan. These "interactive" pipeline scripts are provided in HIPE and explained in the data reduction guides.
 
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  • HIPE (Herschel Interactive Processing Environment): The latest User Release HCSS version that you should use for reducing PACS data is HIPE v11.1 It can be downloaded from: http://herschel.esac.esa.int/HIPE_download.shtml. In the CIB (continuous integration build) this version corresponds to Track 11, build 3010.
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HIPE and data reduction documentation

  • 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 v11.1 It can be downloaded from: http://herschel.esac.esa.int/HIPE_download.shtml. In the CIB (continuous integration build) this version corresponds to Track 11, build 3010. (The CIB is the continuously bug-fixed/upgraded/improved version of HIPE, which every X months becomes a stable User Release. The CIB has the latest software in it, but it will not be bug-free.)
 
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  • Within HIPE you can access all the PACS data reduction documentation and the general HCSS and HIPE -user documentation for Track 11. 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):
 
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Note that within the standalone pdf 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.
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  • The documentation-set provided via HIPE includes the following:
    • The PACS(and HIFI and SPIRE) DRGs. The main function of the "PDRGs" is to take you through reducing your data with the interactive pipelines. They also show you how to quick-look at the already-reduced data you get from the HSA, what to consider before and after reducing your data, and explain what is contained in the PACS data products you get from the HSA.
    • A guide to using HIPE itself (i.e. HIPE as a GUI rather than a scientific tool).
    • A Data Reduction Guide, which is about working with all Herschel (or any other) data in HIPE: the various data analysis tools and data viewers are explained here
    • A Scripting Guide: the language of HIPE is "HIPE's version of jython", and it is intended to be a full scripting environment in which you can manipulate data, do mathematics, and view data in various ways. The "SG" is a guide to scripting in HIPE, although you should be comfortable with scripting yourself (preferably with python, jython, or JAVA) before embarking on scripting in HIPE.
    • Reference manuals, for most of the tasks that you can find in HIPE, and to all the product classes that you can find in HIPE (these tell you e.g. how to manipulate spectra and images directly by querying on the product, rather than using a pre-provided task).
 
  • The what's new in HIPE 11 page lists the changes in HIPE version 11.1 with respect to the 10.x series, provides a detailed lists of updated functionalities and calibration aspects.

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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 June 2013 for photometry are provided here for 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.
  • The PACS Launch Pads from July 2013 (for Track 11) are provided here for spectroscopy. 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. In addition, we take you through all the things you need to think about before reprocessing your PACS spectroscopy through the pipeline yourself:
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Cookbooks and interactive pipeline scripts

  • The pipeline scripts can be seen as cookbooks since they take you through each pipeline flavour, 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 PDRGs explain in more detail what each pipeline task does and how to work your way through the more critical stages of the pipeline. The PDRGs also explain how to decide which pipeline flavour(s) to run on your data.
  • The PACS Launch Pad from June 2013 for photometry are provided here for photometry. This is taken from the first chapter of the PDRGs and is 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.
  • The PACS Launch Pad from July 2013 for spectroscopy (for Track 11) are provided here for spectroscopy. This is taken from the first chapter of the PDRGs and is 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. In addition, we take you through all the things you need to think about before reprocessing your PACS spectroscopy through the pipeline yourself:
 
    • why we recommend you do re-pipeline your data
    • what you need to pay attention to for different types of astronomical source
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    • what the post-pipeline processing tasks are you can, or must, do.
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    • what the post-pipeline processing tasks are you can, or must, do
  Tutorials and scripts:
  • See the various walkthroughs on the NHSC PACS page.
  • 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.
  • In HIPE there is a Scripts menu in which you can find various "useful scripts" for working with PACS data in HIPE. For example, for spectroscopy there is a script showing how to fit the spectra in cubes and make integrated flux images from them; for photometry we show how to do point source aperture photometry. These are written as scripts which you can open in HIPE and run on a test dataset, and in most cases you can replace the test dataset with your own and take it from there. Please do note that these scripts do not explain how to use the GUI version of the tasks--for this you need to read the PDRGs or the general Data Reduction Guide.
 

PACS calibration file versions

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

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you the release note of the new calibration set, with details about the changes. This is further explained in the PDRGs (chap. 2). Clicking on 'Install' will install the latest calibration files.
 
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  • 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.
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  • When reducing your data in HIPE you will normally use the latest version of the calibration tree that you have on disk (this happens by default), but you can chose to use a previous version instead. How to do this is explained in the PDRGs.
 

PACS calibration and performance

 
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