SWP MXHI Time Dependence

This figure and the one below show the time dependence of SWP NEWSIPS large aperture extractions in the spectra of two stars: tau Sco and zeta Cas. They show ratios of the means of 10 spectra obtained in 1993-94 divided by 10 spectra obtained in 1981-82 for each star for two different wavelength regions. The solid curve is for tau Sco and the dotted one for zeta Cas. Both sets of data were binned to 0.5 Å/point.

Notice the following:

1. The structure in the curves is identical, implying that it is a property of the processing and not intrinsic to the stars, and
2. The structure can be far greater than the random noise, so that this systematic effect will determine the ultimate accuracy of the data in many instances.