The Puoko-nui Photometers

We have developed two versions of a high-speed photometric system that have been designed to efficiently undertake high time precision fast photometry of objects with variability timescales between tens of milliseconds and tens of minutes. Key observing targets have been the pulsating white dwarfs. Puoko-nui South has been used extensively on the one metre telescope at Mt John University Observatory in NZ, while Puoko-nui North has been used on several telescopes in Texas. Key components of each system are: (1) an externally triggered commercial frame-transfer CCD, (2) a custom precision time source based on a microprocessor synchronised to GPS derived signals, and (3) flexible software for both instrumental control and online analysis/display. Puoko-nui South has the added feature of a separate autoguiding system employing a second CCD on an offset guiding mechanism.