All data are plotted on receipt at Princeton; these plots can serve as a quick-look form of data for the Guest Investigator, who may want to study them before deciding in what form to use his data. A few programs are available at Princeton, which the Guest Investigator may elect to use. There are decks available for writing data on tape, as well as for generating plots, with various options concerning plotting and wavelength scales. Data can be punched on cards as well, although this is not usually a convenient form in which to transport them. One Princeton program, called STACK, averages data from multiple scans and plots the data at user-selected scales (this technique is useful for detecting very weak lines).
Background contributions due to charged particles are routinely entered in the disk datasets upon initial reduction of the data, and may be subtracted from the total counts at any later stage of the reduction. Stray light contributions for U2 can be computed on request and entered into the datasets in cases where a continuous U2 scan over a substantial portion of the spectrum is available. Techniques have been developed for approximating the stray light correction for U2 scans of isolated regions, but these corrections are not normally done as a service by Princeton, since non-standardized procedures must be used.