Iqueye, a single photon counting photometer applied to the New Technology Telescope

Context. A new extremely high speed photon-counting photometer, Iqueye, has been installed and tested at the New Technology
Telescope, in La Silla.
Aims. This instrument is the second prototype of a “quantum” photometer being developed for future Extremely Large Telescopes of
30–50 m aperture.
Methods. Iqueye divides the telescope aperture into four portions, each feeding a single photon avalanche diode. The counts from the
four channels are collected by a time-to-digital converter board, where each photon is appropriately time-tagged. Owing to a rubidium
oscillator and a GPS receiver, an absolute rms timing accuracy better than 0.5 ns during one-hour observations is achieved. The system
can sustain a count rate of up to 8 MHz uninterruptedly for an entire night of observation.
Results. During five nights of observations, the system performed smoothly, and the observations of optical pulsar calibration targets
provided excellent results.