Timing Analysis

Photons detected with the Einstein IPC and HRI were time-tagged to a precision of 63 $\mu$sec and 8 $\mu$sec, respectively. Photons detected with the ROSAT PSPC and HRI are time tagged to precision of 61 $\mu$sec. The xtiming package contains tasks which make light curves and search for periodicity.

The input for most timing tasks is a time-sorted .qp file, which is made from a QPOE file by the task timsort. Region masking is usually applied to select only portions of the image, in which case, sorting will occur faster. Outputs of the other tasks are typically ST tables. A one line description of available tasks is given below and can be obtained by typing `help xtiming'.

Trial data sets can be found in the files xdata$snr.qp and rp110590n00.qp, and examples using these are given below. The file rp110590n00.qp is the ROSAT calibration image of the RS CVn star AR Lac. Although not a periodic source, the spacecraft wobble causes the image of the source to be periodically eclipsed by the detector window-support mesh and there is a period of $\approx$100 sec in the resultant signal.