The Post-Reduction Off-line Software (PROS) is a portable x-ray analysis software system designed to run under NOAO's Image Reduction and Analysis Facility (IRAF).
The PROS system provides IRAF users with tasks that will properly access the x-ray data. In particular, it supplies the tools to take into account the additional parameters peculiar to x-ray imaging data (photon energy and time information may be retained in x-ray images, along with positions), and algorithms for a correct treatment of the errors, based on photon counting statistics. While written specifically for x-ray data, many of the PROS tasks can be used with other data as well. Similarly many IRAF tasks will be useful for x-ray data.
The PROS software includes spatial, spectral, timing, data I/O and conversion routines, plotting applications, and general algorithms for performing arithmetic operations with imaging data. SAOimage, an interactive data display system running under the X-window system, is also fully compatible with the PROS/IRAF system.
The IRAF system, previous to the development of the PROS software, provided many of the features needed to analyze generic astronomical data, optical data in particular. As a result of discussions involving the PROS software development group and the IRAF system developers, features have been added to the `core' IRAF system to support the development of the software for the analysis of x-ray data. Foremost among these new features is the Quick Position-Ordered Event (QPOE) data files, introduced as of the IRAFv2.8 release. These are lists of photons identified by several quantities, including: arrival time, energy and position in the detector. Despite the name, QPOE files can be sorted on time or any other component of the event description.
While the general syntax of the PROS tasks conforms to the IRAF conventions, new advanced features have been added. These include the availability and use of region descriptors integrated with a sky coordinate system. A detailed description of these new features, as well as a full description of the QPOE files, can be obtained from the corresponding on-line help files (help, regions, qpoe, coords or see `help pros' for a full list of help files). The algorithms used in various tasks are documented and are available on line.