NB : this material is not part of the official distribution

Studying periodic and aperiodic variability

A suite of programs (mainly adapted from the RITA timing analysis suite used at IFCTR for Exosat) to produce Fourier spectra or folding search periodograms from XAS time profiles. Includes some XAS graphical utilities.

The programs and procedures currently available are :

Special file formats

The output files produced can be in two physical and two logical formats.
The two physical formats are XAS ASCII (provisionally supported for backward compatibility, and not described here) and XAS binary (recommended and described here), as controlled by the fourout environment variable.
The two logical formats are power spectra/periodograms and folded light curves, which are sub-cases of XAS binary tables, and come in the following variants :

Dedicated environment variables


[1] L.Chiappetti Timing analysis programs at IFCTR. Users' handbook. Version 1. June 1989.
[2] T.J.Deeming, 1975. Ap.Space.Sci. 36, 137
[3] J.D.Scargle, 1982. Ap.J. 263, 835
[4] S.Ferraz-Mello, 1981. A.J. 86, 619
[5] D.A.Leahy et al., 1983. Ap.J. 266, 160