Calibrator Target Project for the Palomar Testbed Interferometer

Long baseline optical and infrared interferometers are capable of resolving stars and measuring their angular diameters. For the longest baseline instruments, virtually all sources are at least partially resolved. This fact presents a unique challenge to optical/IR interferometers in that it can be difficult to identify bright, unresolved sources for use as calibration targets. When distance is known, measurements of angular diameters lead to the fundamental relationship between the luminosity, stellar size and T_eff, which is particularly crucial to test for main sequence stars. Motivated by the astronomical gains of such a study, we have undertaken a program with the Palomar Testbed Interferometer (PTI) to characterize about 130 candidate stars which we have ascertained may make good calibration targets given PTI's particular limitations. Our study has already revealed binary stars for which we are currently determining orbital elements. We will present our findings to date and the methods by which we determine what makes a good calibration target and how these assumptions are substantiated within our sample.