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.

• Introduction
  • What is needed
  • How to get it
  • What to do with it
• Getting started
  • Star tables
    • ASCII source files
    • Format files
    • Manual entry of data
    • Multiple star files
    • Standard-star files
  • Observatory table
  • Horizon tables
  • Instrument file
  • General advice about table files
• Planning your observing run
  • Introduction
  • Preparing to use the planning program
  • Using the planning program
  • Selection criteria
  • Influencing the plan
• Getting the observations
• Reducing the observations
  • Preliminaries
  • Format conversion
  • Reductions --- at last!
    • Robust fits and bad points
    • Subtraction of dark and sky measurements
    • Sky models
    • Using the sky model
  • Choosing a gradient estimator
  • Extinction and transformation models
    • The bias problem
    • Equations of condition
    • Strategy
    • Standard stars
  • Reduction procedure
  • Final results
    • Residual plots
    • Estimated parameters
    • Individual data
    • Logfile output
    • Table file output
  • Interpreting the output
  • Special problems
    • Missing bands
    • Nonlinearity
    • Special systems
    • Marginal nights
    • Sky problems
    • CCD data
    • Problems with star names
• Installation
  • Table files
  • Maximum limits
• A brief history of PEPSYS
• Acknowledgements
• Summary of PEPSYS commands