Pysynphot: A Python Re-Implementation of a Legacy App in Astronomy

Pysynphot is a package that allows astronomers to model, combine, and manipulate the spectra of stars or galaxies in simulated observations. It is being developed to replace a widely used legacy application, SYNPHOT. While retaining the data-driven philosophy of the original application, Pysynphot’s architecture and improved algorithms were developed to address some of its known weaknesses. The language features available in Python and its libraries, including numpy, often enabled clean solutions to what were messy problems in the original application, and the interactive graphics capabilities of matplotlib/pylab, used with a consistent set of exposed object attributes, eliminated the need to write special-purpose plotting methods. This paper will discuss these points in some detail, as well as providing an overview of the problem domain and the object model.