PEPSYS general photometry package

This chapter describes the PEPSYS package for general photometric reductions. The function of photometric reductions is to measure and remove, so far as possible, the instrumental signature from the data. If we regard the Earth's atmosphere as a part of the instrument not under the control of the observer, we see that measuring and correcting for extinction is an important part of this process. PEPSYS performs extinction correction and transformation to a standard system, if possible.

The package contains two main parts: a planning program and a reduction program. The planning program interacts with the user to find out the goals of the observing program, and then produces a schedule of the observations needed to meet those goals efficiently. The reduction program is flexible enough to model most types of photometric observations accurately, and produce reliable estimates of the uncertainties of the parameter values it obtains from the raw data.

In addition, some auxiliary tools are provided to simplify the work of making the required tables.

Because the data reduction must model the instrument and observational procedure as accurately as possible, we must discuss photometric techniques. The recent book by Sterken and Manfroid [22] and an earlier review [10] are good general references. We also discuss the modelling process in some detail, to provide users with some assurance that good models are used.

Please read through the documentation carefully before trying to use the programs! Many problems can be avoided if you are thoroughly familiar with the contents of this chapter.