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AstroData Lexicon

astrodata Grammar

  • AstroDataType >The term refers to a specific type of data, such as

that associated with a particular instrument mode (e.g. GMOS_IMAGE) or reduced type (IFU_CUBED). The associated action is execution of a criteria for correct classification as the given type. < li> + Descriptors >The term refers to high level metadata which conforms across datatypes, as opposed to the lower level metadata in file and extension headers, from which the higher level “descriptors” will be calculated. The associated action is the algorithmic production or calculation of the high level metadata. < li> + Structures >The term refers to a certain data layout, such as hierarchical nesting, and member names to associate these file elements with, so that, for example, a particular extension type in the source MEF will be given a particular member name driven by the structure definition. E.g. the extension named (MDF) can be assigned to the ad.mdf member for type SPECT. < li> + Primitives >The term refers to dataset transformations, and should

be a scientifically meaningful term. This latter requirement ensures that recipes will be scientifically meaningful, since they are composed of series of primitives. Ideally, recipes then contain just the scientifically meaningful structure. More technically, and broadly, the primitive represents a transformation between different Reduction Context states, requiring some bounding input state and producing an output state. The action associated is, of course, to perform the transformation. < li>

AstroTypes, Primitive Sets and Descriptor Calculators

<html><img alt=”GMOS AstroData Type Tree” style=”margin:.5em;padding:.5em; border:1px black solid” width = “90%” src=”http://ophiuchus.hi.gemini.edu/ADMANUALSOURCE/images_types/GMOS- tree.png“/></html>

The core term, upon which everything else relies are the AstroData types. To the right is a directed graph of the GMOS type tree. The “house” shaped elements are the types, with solid lines pointing to child types.

Blue and red rectangular nodes point dashed lines toward the types where primitive sets and descriptor calculators are assigned.