1. Precedents and Motivation

The Gemini Observatory has produced a number of tools for data processing. Historically this has translated into a number of IRAF[1] packages but the lack of long-term support for IRAF, coupled with the well-known difficulty in creating robust reduction pipelines within the IRAF environment, led to a decision to adopt Python as a programming tool and a new package was born: Gemini Python. Gemini Python provided tools to load and manipulate Gemini-produced multi-extension FITS[2] (MEF) files, along with a pipeline that allowed the construction of reduction recipes. At the center of this package was the AstroData subpackage, which supported the abstraction of the FITS files.

Gemini Python reached version 1.0.1, released during November 2014. In 2015 the Science User Support Department (SUSD) was created at Gemini, which took on the responsibility of maintaining the software reduction tools, and started planning future steps. With improved oversight and time and thought, it became evident that the design of Gemini Python and, specially, of AstroData, made further development a daunting task.

In 2016 a decision was reached to overhaul Gemini Python. While the principles behind AstroData were sound, the coding involved unnecessary layers of abstraction and eschewed features of the Python language in favor of its own implementation. Thus, DRAGONS[3] was born, with a new, simplified (and backward incompatible) AstroData v2.0 (which we will refer to simply as AstroData)

This manual documents both the high level design and some implementation details of AstroData, together with an explanation of how to extend the package to work for new environments.


[2]The Flexible Image Transport System
[3]The Data Reduction for Astronomy from Gemini Observatory North and South package