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1.1.1. Revision History

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2. AstroData Class Reference

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1.1.2. Abbreviations Table

  • HDU: Header-Data Unit
  • MEF: Multi-Extension FITS
  • PHU: Primary Header Unit
  • URL: Uniform Resource Locator

1.1.3. Intended Audience

This document is intended for both new and experienced developers using astrodata:

  1. Users of the astrodata package, in conjunction with the astrodata_Gemini configuration package.
  2. Developers creating new configuration packages (types, descriptors, and transformations), e.g. instrument developers.
  3. Potential developers needing to understand the work involved prior to development (e.g. for costing).
  4. Those trying to understand both what the system currently does, it’s design philosophy, and where the package can or is expected to evolve.

1.1.4. Document Structure

This document is meant as an introductory programmer reference for Gemini Observatory’s Python-based data processing package, astrodata. It is intended to serve both as an introductory reference for the actual function interfaces of two primary classes in the astrodata package, as well as a tool for new users to understand the general characteristics of the package. To this end this document contains three related but somewhat distinct sections:

  • Two chapters presenting the API reference manuals for the AstroData and ReductionContext classes, respectively.
  • A chapter on Creating an AstroData configuration Package, written as a hands-on startup guide.
  • A chapter on the Concepts in the AstroData Infrastructure.

The AstroData class is a dataset abstraction for MEF files, while the ReductionContext is the interface for transformation primitives to communicate with the reduction system (eg. access files in the pipeline, parameter information, execution context, and so on including all communication with the system.)

The astrodata package includes only the infrastructure code, but is generally shipped with the astrodata_Gemini configuration package which contains all information and code regarding Gemini data types and type-specific transformations, and with the astrodata_FITS configuration package that contains standard FITS definitions.

The term “astrodata” in this document can refer to three somewhat distinct aspects of the system. There is AstroData the class, which is distinguishable in print by the camel caps capitalization and is the core software element of the system. There is astrodata the importable python package, which from the user’s point of view imports the configurations which are available in the environment, but which strictly speaking contains only the infrustructural code. And there is simply “Astrodata” a loose term for the whole package, including the configuration package and support library.