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Subsections


E.2 Browse Products after OLP


E.2.1 Survey products

These are fully reduced standard data sets, either FITS images or ASCII FITS tables, for survey-type work. Although these products contain fully reduced data, it must be emphasised that the processing is done in a standard and automatic way which does not involve any scientific judgement. These products may serve for statistical or survey-type analysis of large samples.


E.2.2 Icons and postcards

These are static representations in GIF-format of the survey products. Icons are small images intended to give an impression of the data: photometry, an image or a spectrum. Postcards are essentially enlarged icons with annotations added to give users an impression of the flux levels and wavelengths covered. Icons and postcards facilitate a quick-look to scan the data for their particular purposes and identify which data need to be retrieved. These should never be used for scientific work. The postcards are also used to give a quick look impression of the ISO data for a given observation when browsing through ISO information from other archives/databases, in the framework of the Virtual Observatories, within the so-called Postcard Server. Through calling a URL / Java Server Page (JSP) containing the ISO observation identifier, it returns the ISO postcard (GIF image) of this observation and ancillary information embedded into an HTML page (e.g. the observation quality flag or the status of validation of the observation mode used. Links are also provided to specific sections of the ISO Handbook.

A short description follows of the main, instrument-dependent, characteristics of the browse products. More details can be found in the relevant instrument volumes of the ISO Handbook.

  1. CAM

    Survey Products

    These products are the equivalent of the AAR, giving the image from the CMOS file when it exists and CMAP otherwise.

    Icons and Postcards

    The postcard is the image of the survey product projected in RA,DEC coordinates. It contains a grey-scale coded wedge to indicate flux levels. The icon is a small version of the CMAP/CMOS image shown in detector coordinates. For the CAM spectral observations (CAM04) the mean image of all wavelengths is displayed; the spectrum shown is that of the innermost 10$\times$10 pixels. Up to four multi-filter or multi-PFOV measurements (for a given observation) are shown inside the corresponding icon.

  2. LWS

    Survey Products

    The following processing steps are applied to the standard AAR LSAN file:
    1. Remove all data points with bad status
    2. Clip outliers
    3. Remove individual scans which are inconsistent with the majority of the scans
    4. Average the remaining scans for each detector.
    It should be noted that the resulting spectrum is not stitched together nor is it averaged across detectors. Also, no defringing is applied.

    Icons and Postcards

    Postcard and icon are spectra. In the case of a raster map only the spectrum of the central point is presented.

  3. PHT

    Survey Products

    The survey product is the equivalent of AAR. No survey product is derived for polarisation observations.

    Icons and Postcards

    Depending on the observing mode, postcards and icons are: spectrum or flux per filter against wavelength plots (single or multi-filter staring observations with PHT-P, spectrophotometry with PHT-S) flux against aperture size (multi-aperture photometry), image (single filter raster maps with PHT-P and PHT-C) or mosaic (raster map with PHT-S, multi-filter image for PHT-P and PHT-C)

  4. SWS

    Survey Products

    The following processing steps are applied to the standard AAR file:
    1. Remove all data points with bad or unreliable status
    2. Flatfield the data such that all detectors are scaled to the same level
    3. Clip outliers using sigma clipping
    4. Rebin the data to a grid with the nominal resolution
    Icons and Postcards

    Postcard and icon are spectra which are presented in a mosaic form when the observation contains more than one wavelength range.

next up previous contents index
Next: E.3 Other Products Up: E. IDA content details Previous: E.1 Off-Line Products
ISO Handbook Volume I (GEN), Version 2.0, SAI/2000-035/Dc