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How can I carry out PACS spectroscopy of semi-extended sources?
Posted by Mark Kidger, Last modified by Mark Kidger on 14 September 2018 02:21 PM
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As for SPIRE FTS spectroscopy, semi-extended sources provide the user with a very special set of problems, as they are sources of a size intermediate between point sources (i.e. unresolved) and extended sources (clearly resolved), for which neither point source reduction techniques, nor extended source techniques work well. We assume that you have watched the Herschel Science Centre short videotutorial called Starting with PACS Spectroscopy: https://www.youtube.com/watch?v=rcY487Z9Kyg Or, at least, are familiar with the contents of this short videotutorial and its associated documentation. There is a Herschel Science Centre short videotutorial that will guide you through the process of processing and analyzing semi-extended sources. You can find the short videotutorial here: https://www.youtube.com/watch?v=PNSuxM105UY A pre-requisite for processing semi-extended sources is to know: 1. The surface brightness distribution. and 2. The off-set of the source from the centre of the central spaxel. If you do not have this information, you can still attempt to use these techniques (the short videotutorial will advise you on this), but may have larger errors in your calibration. You can find a package of useful support materials for this short videotutorial in the Herschel Explanatory Legacy library (HELL) in the Level 2, Data reduction, PACS spectroscopy section. This short videotutorial you will be shown how to use the useful script that was developed to deal with semi-extended sources that extracts the spectrum of the central spaxel of a re-binned cube and applies a point source correction to it. It then compares the surface brightness of a point source with the known surface brightness distribution and creates an extended-to-point correction too that is used to generate the semi-extended source correction. It will show you how to apply the models and which data products to use for different observing modes. Finally, you will be shown some examples of PACS data processed with the script. We recommend, as background information, that you consult the following Herschel Science Centre short videotutorials too: Point Source Spectroscopy with PACS, https://www.youtube.com/watch?v=nYWTccEQz_M PACS Cubes in Detail, https://www.youtube.com/watch?v=CxZF9-9D8UM Or the following guide: Dealing with extended sources observed with PACS spectroscopy | |
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