XRONOS is a general purpose timing analysis package. Although it was designed mostly for X-ray astronomy, XRONOS is basically detector and wavelength-independent. It has been used to analyse data from the Einstein Observatory, EXOSAT and Ginga, as well as optical photometry and helioseismology data. It includes programs for: light curve(s), hardness ratio and colour-colour plotting, epoch folding, power spectrum, autocorrelation, cross-correlation, time skewness and statistical analysis.
XRONOS consists of a collection of programs, each dedicated to one task, which can be run from the control environment provided by the xronos program. The program xronos is characterised by 3 different user interfaces: a QUESTION/ANSWER user interface, a PARTIAL QUESTION/ANSWER user interface and a COMMAND-DRIVEN user interface. Command files are supported by the question/answer and command-driven user interfaces of XRONOS. XRONOS applications can be run in their command-driven fashion within the EXOSAT Database System.
The new user is advised to read chapter 2 (overview), which gives an overview of XRONOS, and chapter 3 (walk_through), which is a walk-through of a XRONOS session. XRONOS uses the QDP/PLT plotting package which is described briefly in Appendix A and in more detail in the QDP/PLT User's Guide (Tennant 1990).