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CHAPTER 1. INTRODUCTION
The package consists of three main programs, and five support programs:
• mklib: constructs a library of isochrone photometry from raw isochrones.
• synth: constructs synthetic CMDs from the isochrones, applying the effects
of interstellar extinction, binarity, IMF, and photometric errors as appropriate
for the data.
• sfh: performs a maximum-likelihood comparison of composite model CMDs
and input data CMDs. The best-fit star formation history is output.
- interp: interpolates between adjacent isochrones, to improve resolution in
age and/or metallicity. Requires knowledge of equivalent evolutionary points
(EEPs) along each isochrone.
- testpop: constructs artificial stellar populations from the isochrones. testpop
incorporates the photometric errors, extinction, etc. exactly as is done in
synth. These populations can be input to sfh for testing purposes. (testpop
is in the subdirectory of the same name)
- repop: same as testpop, except used to construct an artificial population from the SFH amplitudes found by sfh. This is useful for model/data
comparisons. (repop is in the subdirectory of the same name)
- testchi: allows one to examine the parameter space of the fit by hand.
SF amplitudes and other parameters can be interactively adjusted, and the
resulting fit recomputed on the fly. (testchi is in the subdirectory of the
same name)
- mkimages.sh: creates CMD images from the best-fit model. It also creates
CMD maps of each region’s contribution to the fitting statistic.