skew mapping back to top previous page

the problem: you want to detect the faint secondary star in your time-resolved data, but simply averaging the spectra together smears out any weak features from the star.
a possible solution: cross-correlate your time-resolved spectra with a template of matched spectral-type and then average the data with these velocity shifts removed.
why this sometimes fails: the secondary star features are too weak to give well-defined cross-correlation peaks.
another possible solution: back project the cross-correlation peaks to form a skew map (Smith, Collier Cameron, Tucknott, 1993, Cataclysmic Variables & Related Objects, eds Regev & Shaviv, IoP: Bristol, 70).