Key software architecture decisions for the automated planet finder

The Automated Planet Finder (APF) at Lick Observatory on Mount Hamilton is a modern 2.4 meter computer controlled telescope. At one Nasmyth focus is the Levy Spectrometer, at present the sole instrument used with the APF. The primary research mission of the APF and the Levy Spectrometer is high-precision Doppler spectroscopy. Observing at the APF is unattended; custom software written by diverse authors in diverse languages manage all aspects of a night’s observing. This paper will cover some of the key software architecture decisions made in the development of autonomous observing at the APF. The relevance to future projects of these decisions will be emphasized throughout.