Filling Out the Spectral Dictionary Classes

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The Spectral Dictionary is a discipline dictionary, which means that its classes will appear in the <Discipline_Are> at the bottom of the <Observation_Area> in observational product labels (and in the <Context_Area>, if appropriate, in non-observational products). The classes in this dictionary describe the spectral characteristics of the data objects presented in the product.

The standard abbreviation for the Spectral Discipline Dictionary namespace is "sp:". Typically, every class and attribute from this dictionary would be prefixed with the "sp:" abbreviation, but this has been omitted in these pages in the interest of readability. See the "Namespace References" section of the "Schema Reference in PDS4 Labels" page for additional information on ways of typing attributes and classes to namespaces.

Update: 19 April 2017 - begin re-write for new Spectral Dictionary nearing the end of development



This is the wrapper class for spectral characteristics. Repeat it once for each spectral-type object you have in your observational product. The Spectral Discipline Dictionary can currently accommodate spectra measured in wavelength, wavenumber, and frequency that are presented as either image cubes, images, or tables (i.e., linear spectra where each row presents one point in the spectrum).

If you have a different type of spectrum, contact Anne Raugh at the Small Bodies Node at the University of Maryland for assistance.



This is a free-format text field you can use to provide any additional explanation or caveats about the information that follows that would be helpful to an end user.



Use this class to identify the spectral-type data object in this product for which this class provides the characteristics. Typically, an observational product will contain only a single spectral object (though it might be a spectral cube). This class is required even in that case.

Note that this class and its elements are in the pds: core namespace, rather than the Spectral Dictionary namespace, so you will need to make the appropriate change of namespace for this class. See "Schema Referencing in PDS4 Labels: Namespace References" for details.



This is a free-format text field that you can use if there is something about the relationship between the referenced spectrum and its characteristics that requires additional explanation.



This attribute must contain a <local_identifier> string of a spectral data object described elsewhere in this label. Spelling and capitalization count.



This attribute must have one of these values:

  • spectral_characteristics_to_array_object
  • spectral_characteristics_to_table_object

The value you use must correspond to the type of the data object you're linking to. So if your local_identifier points to an Array_2d_Spectrum then the local_reference_type must be spectral_characteristics_to_array_object. If your local_identifier points to a linear spectrum in a Table_Character object, then the local_reference_type must be spectral_characteristics_to_table_object.



This attribute indicates the unit of measure for the spectral bin dimensions. It must be one of the following vaues:

  • frequency
  • wavelength
  • wavenumber

The bin descriptions you provide in the subsequent classes and attributes must correspond to the spectral_bin_type specified here.



This class provides known spectral attributes of the target observed (as identified in the <Target_Identification> area of the label). The class may be omitted if it is not needed.