S-lang/ISIS Timing Analysis Routines (SITAR) Home Page

SITAR, S-lang/ISIS Timing Analysis Routines, presents a set of functions and subroutines designed to be run within ISIS or Sherpa in order to perform timing analysis of data. The specific examples presented here relate to data obtained with the Chandra X-ray Satellite or with the Rossi X-ray Timing Explorer-All Sky Monitor (RXTE-ASM). It is hoped that these routines will serve as proto-types for tools that will be included with future releases of CIAO, the Chandra Interactive Analysis of Observations software package; however, they are functional and useful as they stand.

The subroutines are written in S-Lang, with some reliance on functions intrinsic to ISIS or the S-Lang Modules Packages. Headers of the subroutines clearly delineate these functions, so that the routines can be easily adapted to other s-lang based analysis systems. These routines will run in ISIS versions 1.1.5 and greater, although selected routines (Bayesian Blocks) are able to run in ISIS versions >1.0.48. Alternatively, they can be run in Sherpa, as found in CIAO 3.0.2. No additional packages are required if these routines are used within ISIS or Sherpa. (Additional features, namely increased options for the choice of `prior' in the `event mode' of the Bayesian Blocks routine, and the proper statistical significances of epoch fold values, are available with the download of the GNU Scientific Library module available from the S-Lang Modules Packages.)

Note that as of SITAR version 0.3.0, there should be no difference in functionality of these routines as run in either ISIS or Sherpa.

Currently, SITAR provides a set of routines for:

• Performing a Bayesian Blocks decomposition of a lightcurve, based upon an algorithm and MATLAB codes developed by Jeffrey Scargle.
• Reading RXTE-ASM lightcurves
• Rebinning rate lightcurves, and rebinning power spectra
• Period and epoch-folding rate lightcurves
• Power and Cross Power Spectral Density functions

• Kolmolgorov-Smirnov and Kuiper tests
• Rayleigh Z-test
• Z-transformed discrete cross correlations
• Lomb-Scargle periodograms
• Dynamical Power Spectra, displayed via DS9 using the SLXPA module